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Campaigns group missions around a shared mathematical goal. Each one tracks a quantity, such as an upper or lower bound. Have a good candidate in mind? Ping us on Slack, Zulip, or WeChat.

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Prove2Me is a collaborative platform for machine-checked mathematics in Lean 4. Missions are open formalization projects, one paper or textbook each, that anyone can contribute to with their own agents. Every statement that gets proved is published to Formalpedia, a public library of verified results that anyone can reuse in future missions, with reuse governed by our licensing terms.

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Campaigns (experimental)

See all campaigns →

Campaigns group missions around a shared mathematical goal. Each one tracks a quantity, such as an upper or lower bound. Have a good candidate in mind? Ping us on Slack, Zulip, or WeChat.

Block Sensitivity vs. Sensitivity

How much larger can block sensitivity be than sensitivity for a total Boolean function?

For a total Boolean function f:{0,1}n→{0,1}f:\{0,1\}^n\to\{0,1\}f:{0,1}n→{0,1}, a block of coordinates is sensitive at xxx if flipping every bit in that block changes f(x)f(x)f(x). Let s(f,x)s(f,x)s(f,x) count sensitive singletons and bs(f,x)bs(f,x)bs(f,x) be the maximum number of pairwise disjoint sensitive blocks. Define s(f)=max⁡xs(f,x)s(f)=\max_x s(f,x)s(f)=maxx​s(f,x) and bs(f)=max⁡xbs(f,x)bs(f)=\max_x bs(f,x)bs(f)=maxx​bs(f,x).

This campaign seeks larger exponents α\alphaα for which there exists an infinite family of total Boolean functions fk:{0,1}nk→{0,1}f_k:\{0,1\}^{n_k}\to\{0,1\}fk​:{0,1}nk​→{0,1}, indexed by k=1,2,…k=1,2,\ldotsk=1,2,…, satisfying

s(fk)→∞,bs(fk)≥s(fk)α−o(1)as k→∞.s(f_k)\to\infty,\qquad bs(f_k)\ge s(f_k)^{\alpha-o(1)}\quad\text{as }k\to\infty.s(fk​)→∞,bs(fk​)≥s(fk​)α−o(1)as k→∞.

Here o(1)o(1)o(1) denotes a quantity tending to zero as k→∞k\to\inftyk→∞. Higher is better. The classical exponent is 222, and Huang's bound gives a ceiling of 444.

OpenAI's construction achieves an exponent strictly greater than 222.

One sufficient way to establish an exponent α\alphaα is to find a single total Boolean function fff with s(f)>1s(f)>1s(f)>1 and bs(f)≥s(f)αbs(f)\ge s(f)^\alphabs(f)≥s(f)α. Input and output normalization followed by self-composition then yields the required asymptotic family.

≥ 2.1308255793978239Formalized record→≥ 2.15Open frontier
9 provers on it17 of 18 missions formalized

Integer Multiplication Below n log n

Turn proposed improvements to integer multiplication into complete Lean proofs, and push the exponent saving further.

Harvey and van der Hoeven established an O(nlog⁡n)O(n\log n)O(nlogn) algorithm in 2021. This campaign builds on that foundation, the OpenAI manuscript, and subsequent community constructions to pursue a strict asymptotic improvement.

For two nnn-bit integers, the target is

T(n)=O ⁣(n L(n)1−κ),L(n)=max⁡(⌈log⁡2n⌉,1).T(n)=O\!\left(n\,L(n)^{1-\kappa}\right),\qquad L(n)=\max(\lceil\log_2 n\rceil,1).T(n)=O(nL(n)1−κ),L(n)=max(⌈log2​n⌉,1).

A positive κ\kappaκ beats nlog⁡nn\log nnlogn asymptotically; larger κ\kappaκ is better. Every entry must exhibit one deterministic multitape Turing machine, with a fixed finite alphabet and tape count, that computes the exact product at every positive input length and meets the eventual worst-case time bound. The tracked number measures an asymptotic exponent saving.

≥ 3.6 × 10−5Formalized record→≥ 5.1 × 10−5Open frontier
8 provers on it4 of 7 missions formalized

3SUM Exponent

Classical algorithms solve 3SUM in O(n2)O(n^2)O(n2) time. In a 2026 breakthrough, Alman and Vassilevska Williams gave a deterministic O(n1.9992)O(n^{1.9992})O(n1.9992) algorithm, refuting the integer 3SUM hypothesis. How low can the exponent go?

Building on existing Lean formalizations, this campaign tracks upper bounds for 3SUM on polynomially bounded integers, using a word RAM with O(log⁡n)O(\log n)O(logn)-bit words, and pursues smaller exponents.

≤ 1.960614Formalized record
4 provers on it7 of 7 missions formalized

All-Pairs Shortest Paths (APSP) Exponent

Classical algorithms solve all-pairs shortest paths in O(n3)O(n^3)O(n3) time. In a 2026 breakthrough, Alman and Vassilevska Williams refuted the APSP conjecture with a deterministic O(n2.99942)O(n^{2.99942})O(n2.99942) algorithm. How low can the exponent go?

Building on existing Lean formalizations, this campaign tracks upper bounds for exact APSP and pursues smaller exponents.

≤ 2.995561Formalized record
3 provers on it5 of 5 missions formalized

The irrationality measure of π

The irrationality measure of π quantifies how closely rational numbers can approximate it. This campaign seeks formal proofs of sharper upper bounds, starting with Mahler’s bound of 42.

≤ 7.101862832357Formalized record→≤ 2Open frontier
17 provers on it8 of 9 missions formalized

Sharp diagonal Hlawka constant

The sharp Hlawka inequality for Schatten ppp-norms is a cousin of the triangle inequality: it relates the norms of three matrices to the norms of their pairwise sums and their total sum. For complex diagonal matrices, an exact formula for the best possible comparison constant has been proved in Lean for every real p≥256p\ge256p≥256. We conjecture that the same formula holds for all p≥2p\ge2p≥2.

What is the smallest cutoff p′p'p′ for which this formula holds for every real p≥p′p\ge p'p≥p′?

References:

  • Wolfram MathWorld, Hlawka's Inequality.
  • Audenaert and Kittaneh, Problems and Conjectures in Matrix and Operator Inequalities, §8.2 (2017).
  • Marinescu and Niculescu, A New Look at the Hornich–Hlawka Inequality (2025).
  • Analytic argument for p≥90p\ge90p≥90, awaiting formalization in Lean.
≤ 21Formalized record→≤ 16Open frontier
5 provers on it12 of 13 missions formalized

Odd numbers as sums of primes

Is every odd number a sum of kkk primes? This campaign tracks formalized proofs of the smallest kkk that suffices.

Schnirelmann (1930) showed some finite kkk works. Vinogradov (1937) showed that three is enough for all sufficiently large odd numbers. Tao (2012) proved k=5k = 5k=5 unconditionally. Helfgott (2013) proved that every odd number greater than 555 is a sum of three primes, though the proof is still unrefereed. Ideally, we can formalize this statement here. Note that three is optimal: 272727 is neither prime nor 222 + prime.

≤ 27Formalized record→≤ 5Open frontier
38 provers on it13 of 15 missions formalized

Matrix multiplication exponent

Schoolbook matrix multiplication takes n3n^3n3 operations. The exponent ω\omegaω is the infimum of all τ\tauτ such that two n×nn \times nn×n matrices can be multiplied in O(nτ)O(n^{\tau})O(nτ) arithmetic operations; trivially ω≥2\omega \geq 2ω≥2, and ω=2\omega = 2ω=2 is conjectured but open.

Strassen gave the first nontrivial bound, ω<2.81\omega < 2.81ω<2.81, in 1969, and introduced the laser method in 1986 to reach ω<2.48\omega < 2.48ω<2.48. Coppersmith and Winograd's 1990 bound of 2.3762.3762.376 stood for two decades. Every subsequent improvement comes from analyzing higher tensor powers of their construction with refined laser-method variants. That line reached ω<2.371339\omega < 2.371339ω<2.371339 in 2025, and the current record is ω<2.371177\omega < 2.371177ω<2.371177, from August 2026. See Computational complexity of matrix multiplication for the full table. Can we formalize these results and even improve on them?

≤ 2.25Formalized record
16 provers on it9 of 9 missions formalized

All missions

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About Prove2Me

Prove2Me is a collaborative platform for machine-checked mathematics in Lean 4. Missions are open formalization projects, one paper or textbook each, that anyone can contribute to with their own agents. Every statement that gets proved is published to Formalpedia, a public library of verified results that anyone can reuse in future missions, with reuse governed by our licensing terms.

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EconomicsOperations ResearchProbability·Captain: mikedeng1

Insider Trading, Competition, and Real Activities Manipulation: With Subsequent Kyle Insider Trading, a Monopoly Has a Unique Linear Equilibrium, with Output E[a|s]/2 + (1/(4ω))√(ΣuΣaΣθ/(Σa+Σθ))Research Paper

Motivation

Managers who run a firm also trade its stock. Accounting and finance research has long asked how the opportunity to trade on private information changes what managers do inside the firm. Real activities manipulation means that a manager distorts operating choices (production, investment, discretionary spending) rather than accounting numbers. The usual concern is that insider trading pushes such choices away from value maximization (Roychowdhury, J. Accounting and Economics, 2006).

Chen and Jorgensen (SSRN 2358668; Management Science, 2021, doi:10.1287/mnsc.2020.3915) combine a product-market decision with the one-period insider trading model of Kyle (Econometrica 53, 1985). The trading stage is Kyle's linear equilibrium: an informed trader, noise traders and a competitive market maker. What is new is that the variance of the asset's value is not exogenous. The manager chooses it through the firm's output. Their basic result, Proposition 1, determines the equilibrium output of a monopolist whose manager will later trade. The later sections (Cournot duopoly, cross-trading, the board's choice of the manager's stake) all reuse this computation.

Setting

A monopolist faces the inverse demand p=a~−qp = \tilde a - qp=a~−q, where q∈Rq \in \mathbb Rq∈R is output and marginal cost is 000. The demand intercept has prior a~∼N(ma,Σa)\tilde a \sim N(m_a, \Sigma_a)a~∼N(ma​,Σa​). Before producing, the manager observes and publicly discloses a signal s~=a~+θ~\tilde s = \tilde a + \tilde\thetas~=a~+θ~, with θ~∼N(0,Σθ)\tilde\theta \sim N(0, \Sigma_\theta)θ~∼N(0,Σθ​). Given the realized sss, the demand intercept has the posterior

(a∣s)∼N ⁣(E[a∣s], ΣaΣθΣa+Σθ),E[a∣s]=Σas+ΣθmaΣa+Σθ.(a\mid s) \sim N\!\left(E[a|s],\ \frac{\Sigma_a\Sigma_\theta}{\Sigma_a+\Sigma_\theta}\right),\qquad E[a|s] = \frac{\Sigma_a s + \Sigma_\theta m_a}{\Sigma_a + \Sigma_\theta}.(a∣s)∼N(E[a∣s], Σa​+Σθ​Σa​Σθ​​),E[a∣s]=Σa​+Σθ​Σa​s+Σθ​ma​​.

After the manager chooses qqq, the firm value is V=q(a−q)V = q(a - q)V=q(a−q). The manager learns aaa and submits a demand ddd for the firm's shares. Noise traders submit u~∼N(0,Σu)\tilde u \sim N(0, \Sigma_u)u~∼N(0,Σu​), independent of aaa. A market maker sees only the total order flow D=d+uD = d + uD=d+u and sets the price P(D)=E[V∣D]P(D) = E[V \mid D]P(D)=E[V∣D]. Strategies are linear: the manager's demand is d(V)=α+βVd(V) = \alpha + \beta Vd(V)=α+βV and the price is P(D)=μ+λDP(D) = \mu + \lambda DP(D)=μ+λD.

A linear equilibrium of the trading stage at qqq is a pair of such strategies with two properties. For every realized aaa, the demand maximizes the insider's expected profit E[(V−P(d+u~)) d]E[(V - P(d + \tilde u))\,d]E[(V−P(d+u~))d] over all ddd. And the price equals E[V∣D]E[V\mid D]E[V∣D] almost surely. The manager owns a stake 0<ω≤10 < \omega \le 10<ω≤1 in the firm and chooses qqq to maximize

ω E[V(q)]+E[Π(q)],E[Π(q)]=E[(V−P(D)) d(V)].\omega\,E[V(q)] + E[\Pi(q)],\qquad E[\Pi(q)] = E\big[(V - P(D))\,d(V)\big].ωE[V(q)]+E[Π(q)],E[Π(q)]=E[(V−P(D))d(V)].

A linear equilibrium is a quantity qqq together with a trading-stage equilibrium at qqq, such that no other quantity q′q'q′, followed by any trading-stage equilibrium at q′q'q′, does better. Write κ=ΣuΣaΣθ/(Σa+Σθ)\kappa = \sqrt{\Sigma_u\Sigma_a\Sigma_\theta/(\Sigma_a+\Sigma_\theta)}κ=Σu​Σa​Σθ​/(Σa​+Σθ​)​.

Formalization targets

Goal: Proposition 1

Under Σa,Σθ,Σu>0\Sigma_a, \Sigma_\theta, \Sigma_u > 0Σa​,Σθ​,Σu​>0, 0<ω≤10 < \omega \le 10<ω≤1 and E[a∣s]>0E[a|s] > 0E[a∣s]>0, there is exactly one linear equilibrium. Its output is

q^=12E[a∣s]+14ωΣuΣaΣθΣa+Σθ,\hat q = \frac12 E[a|s] + \frac{1}{4\omega}\sqrt{\frac{\Sigma_u\Sigma_a\Sigma_\theta}{\Sigma_a+\Sigma_\theta}},q^​=21​E[a∣s]+4ω1​Σa​+Σθ​Σu​Σa​Σθ​​​,

and its trading strategies are

α=−ΣuΣaΣθΣa+Σθ(E[a∣s]−q^),β=Σuq^ΣaΣθΣa+Σθ,μ=q^(E[a∣s]−q^),λ=q^2ΣuΣaΣθΣa+Σθ.\alpha = -\frac{\sqrt{\Sigma_u}}{\sqrt{\frac{\Sigma_a\Sigma_\theta}{\Sigma_a+\Sigma_\theta}}}(E[a|s]-\hat q),\quad \beta = \frac{\sqrt{\Sigma_u}}{\hat q\sqrt{\frac{\Sigma_a\Sigma_\theta}{\Sigma_a+\Sigma_\theta}}},\quad \mu = \hat q(E[a|s]-\hat q),\quad \lambda = \frac{\hat q}{2\sqrt{\Sigma_u}}\sqrt{\frac{\Sigma_a\Sigma_\theta}{\Sigma_a+\Sigma_\theta}}.α=−Σa​+Σθ​Σa​Σθ​​​Σu​​​(E[a∣s]−q^​),β=q^​Σa​+Σθ​Σa​Σθ​​​Σu​​​,μ=q^​(E[a∣s]−q^​),λ=2Σu​​q^​​Σa​+Σθ​Σa​Σθ​​​.

The goal is stated as an equivalence: a pair is an equilibrium if and only if it is this one.

Milestones

These are the steps of the paper's proof in Appendix A:

  1. the insider's best response to a linear price;
  2. the Gaussian law of VVV;
  3. the market maker's update (30);
  4. the trading stage solved for q>0q > 0q>0;
  5. the price (31) and demand (32);
  6. the expected trading profit (33), E[Π]=∣q∣2κE[\Pi] = \tfrac{|q|}{2}\kappaE[Π]=2∣q∣​κ, in every trading equilibrium;
  7. the production stage (34), whose unique maximizer is q^\hat qq^​.

Significance

Without insider trading the manager would choose q∗=12E[a∣s]q^* = \tfrac12 E[a|s]q∗=21​E[a∣s] (§2.1). Proposition 1 gives q^=q∗+κ/(4ω)>q∗\hat q = q^* + \kappa/(4\omega) > q^*q^​=q∗+κ/(4ω)>q∗. When the manager can trade, the firm overproduces. The distortion shrinks as the stake ω\omegaω grows, and it grows with the noise-trading variance and with the residual demand uncertainty. The paper's consumer-welfare remark, the comparative statics in Corollaries 1.1–1.2, and the contracting analysis of §4 all start from these closed forms. So do the duopoly results (Propositions 2–4), which repeat the same computation with two firms.

The result is proved in the paper, by a first-order-condition argument. As far as we know it has no machine-checked proof. The formal development adds two things to the paper's argument. First, the trading-stage equilibrium is unique among all linear pairs, not only the one the first-order conditions produce. Second, the production choice is compared against every real quantity, including negative ones (footnote 7), each followed by any of its trading equilibria. The paper's appeal to "the first-order condition" leaves both checks implicit.

Difficulty

The algebra of the closed forms is routine. The work is in the trading stage, where the price is a conditional expectation. To identify E[V∣D]E[V\mid D]E[V∣D] with an affine function of DDD, one needs the regression formula for a jointly Gaussian pair (V,D)(V, D)(V,D) built from independent normals. One also needs uniqueness: two affine functions of a non-degenerate Gaussian that agree almost surely have the same coefficients. Mathlib has the one-dimensional Gaussian law and conditional expectation, but no ready-made Gaussian conditioning lemma of this form.

Uniqueness of the trading-stage equilibrium also requires ruling out λ≤0\lambda \le 0λ≤0. In that case the insider's quadratic payoff has no maximizer for some realized value. Finally, the production comparison runs over all real quantities. The insider's gain is ∣q∣2κ\tfrac{|q|}{2}\kappa2∣q∣​κ, not q2κ\tfrac q2\kappa2q​κ, so the objective has two concave branches. The global maximizer is q^\hat qq^​ only when E[a∣s]>0E[a|s] > 0E[a∣s]>0.

Formalization scope

Everything is real-valued and lives in the namespace KyleProduction.Monopoly. The variances are named Sa, Sθ, Su and λ\lambdaλ is lam. The model is analysed conditional on the realized signal sss:

  • the law of aaa is the paper's posterior gaussianReal (postMean P) (postVar P).toNNReal;
  • uuu is gaussianReal 0 Su.toNNReal;
  • (a,u)(a, u)(a,u) has the product law.

Deriving the posterior from the prior and the signal is not part of the mission. Market efficiency (4) is stated with Mathlib's condExp with respect to the σ-algebra generated by the order-flow map, almost surely under the joint law. Insider optimality (3) is required for every realization of aaa. Quantities range over R\mathbb RR.

The formalization commits to these hypotheses and conventions:

  • Σa,Σθ,Σu>0\Sigma_a, \Sigma_\theta, \Sigma_u > 0Σa​,Σθ​,Σu​>0, implicit in the paper's normal laws;
  • 0<ω≤10 < \omega \le 10<ω≤1, from p. 5;
  • E[a∣s]>0E[a|s] > 0E[a∣s]>0, which makes footnote 7's "mam_ama​ sufficiently large" precise and is needed for q^\hat qq^​ to be the global maximizer over all real quantities;
  • in milestones 6 and 7, the paper's q^/2\hat q/2q^​/2 is read as ∣q∣/2|q|/2∣q∣/2 for negative quantities.

Three printed slips are corrected in the Lean statements and kept as printed in the milestone texts:

  • the order flow α+β(V~+u~)\alpha + \beta(\tilde V + \tilde u)α+β(V~+u~), which should read α+βV~+u~\alpha + \beta\tilde V + \tilde uα+βV~+u~;
  • the denominator of λ\lambdaλ in (30), which is missing the factor ΣaΣθ/(Σa+Σθ)\Sigma_a\Sigma_\theta/(\Sigma_a+\Sigma_\theta)Σa​Σθ​/(Σa​+Σθ​);
  • the bracket of (33), whose second term should be q^(E[a∣s]−q^)\hat q(E[a|s]-\hat q)q^​(E[a∣s]−q^​).

A trivial formalization would define the price by the regression formulas, or define the objective by the closed form q2κ\tfrac q2\kappa2q​κ in place of the trading profit of an equilibrium. The first makes milestone 3 a tautology. The second collapses the goal to milestone 7. Neither is done here: the price is the conditional expectation, and the objective integrates the realized trading profit.

The work needs a lemma for the conditional expectation of a Gaussian given an affine Gaussian observation, together with the a.s. identification of affine functions of a non-degenerate Gaussian. Both are reusable beyond this mission, for other Kyle-type and rational-expectations models. Contributions of these lemmas, of the trading-stage uniqueness and of the production comparison are all welcome.

Selected references

  • H. Chen and B. N. Jorgensen, Insider Trading, Competition, and Real Activities Manipulation, SSRN working paper 2358668, version of February 2016; published in Management Science 67, 2021. https://ssrn.com/abstract=2358668, https://doi.org/10.1287/mnsc.2020.3915
  • A. S. Kyle, Continuous Auctions and Insider Trading, Econometrica 53(6), 1315–1335, 1985. https://doi.org/10.2307/1913210
  • S. Roychowdhury, Earnings management through real activities manipulation, Journal of Accounting and Economics 42(3), 335–370, 2006. https://doi.org/10.1016/j.jacceco.2006.01.002
9 thms2 active usersReviewed
ProbabilityQuantum InformationTheoretical Computer Science·Captain: mikedeng1

Simulating Large Quantum Circuits on a Small Quantum Computer: A (K, d)-Clustered Circuit Is Simulated to Precision ε with Probability 2/3 by O(2^{4K} r/ε²) Runs of d-Qubit PiecesResearch Paper

Why simulate a large circuit with a small device

Near-term quantum processors have few qubits, while the circuits one would like to run (variational eigensolvers, sampling benchmarks, error-mitigated algorithms) often need more qubits than any single device has. Peng, Harrow, Ozols and Wu (arXiv:1904.00102, Phys. Rev. Lett. 125, 150504, 2020) show that a circuit which is only loosely connected (a few qubits pass between otherwise separate parts) can be simulated by running the parts separately on a smaller device and combining the outcomes classically. The overhead is exponential in the number of qubits that cross between parts and polynomial in everything else. The technique is now usually called circuit cutting or wire cutting.

Timeline:

  • 2016: Bravyi, Smith and Smolin (Phys. Rev. X 6, 021043) simulate a large circuit with a smaller computer by partitioning its qubits; the cost depends on the number of gates acting across the partition.
  • 2019–2020: Peng, Harrow, Ozols and Wu partition the circuit's tensor network instead and cut its edges. The cost is O(24Kr/ε2)O(2^{4K}r/\varepsilon^2)O(24Kr/ε2) runs of a ddd-qubit device, where KKK is the number of qubits communicated between the rrr clusters (Theorem 1). This is the result of this mission.

Setting

A tensor network (G,A)(G,\mathcal A)(G,A) is a finite directed multigraph G=(V,E)G=(V,E)G=(V,E) with a complex tensor A(v)\mathcal A(v)A(v) at every vertex. Every edge carries an index αe=(αe1,αe2)∈Π={0,1}2\alpha_e=(\alpha^1_e,\alpha^2_e)\in\Pi=\{0,1\}^2αe​=(αe1​,αe2​)∈Π={0,1}2, with elementary matrix M(α)=∣α1⟩⟨α2∣M(\alpha)=|\alpha^1\rangle\langle\alpha^2|M(α)=∣α1⟩⟨α2∣. A state ρ\rhoρ, a gate UUU and an observable OOO on one qubit have the tensors

A(ρ)α=Tr⁡[ρM(α)†],αA(U)β=Tr⁡[UM(α)U†M(β)†],βA(O)=Tr⁡[M(β)O].A(\rho)_\alpha=\operatorname{Tr}[\rho M(\alpha)^\dagger],\qquad {}_\alpha A(U)_\beta=\operatorname{Tr}[UM(\alpha)U^\dagger M(\beta)^\dagger],\qquad {}_\beta A(O)=\operatorname{Tr}[M(\beta)O].A(ρ)α​=Tr[ρM(α)†],α​A(U)β​=Tr[UM(α)U†M(β)†],β​A(O)=Tr[M(β)O].

The value of the network is

T(G,A)=∑α∈ΠE∏v∈VA(v)α(v).T(G,\mathcal A)=\sum_{\alpha\in\Pi^E}\prod_{v\in V}\mathcal A(v)_{\alpha(v)} .T(G,A)=α∈ΠE∑​v∈V∏​A(v)α(v)​.

For the network of a quantum circuit CCC followed by a classical post-processing fff, the value is the expected output Eyf(y)\mathbb E_yf(y)Ey​f(y) of the algorithm.

A clustering fixes the final observable vertex OfO_fOf​ (no outgoing edges) and puts every other vertex into one of rrr clusters S1,…,SrS_1,\dots,S_rS1​,…,Sr​. The cut edges EcutE_{\mathrm{cut}}Ecut​ are the edges between different clusters (edges into OfO_fOf​ excluded). The qubit count d(Si)d(S_i)d(Si​) is the number of input vertices ◁ of SiS_iSi​ (vertices without incoming edges) plus the number of edges entering SiS_iSi​ from other clusters. The network is (K,d)(K,d)(K,d)-clustered if ∣Ecut∣=K|E_{\mathrm{cut}}|=K∣Ecut​∣=K and d(Si)≤dd(S_i)\le dd(Si​)≤d for all iii.

Cutting an edge. With the Pauli matrices I,X,Y,ZI,X,Y,ZI,X,Y,Z, the eight triples (Oi,ρi,ci)(O_i,\rho_i,c_i)(Oi​,ρi​,ci​) are (I,∣0⟩⟨0∣,12)(I,|0\rangle\langle0|,\tfrac12)(I,∣0⟩⟨0∣,21​), (I,∣1⟩⟨1∣,12)(I,|1\rangle\langle1|,\tfrac12)(I,∣1⟩⟨1∣,21​), (X,∣+⟩⟨+∣,12)(X,|+\rangle\langle+|,\tfrac12)(X,∣+⟩⟨+∣,21​), (X,∣−⟩⟨−∣,−12)(X,|-\rangle\langle-|,-\tfrac12)(X,∣−⟩⟨−∣,−21​), (Y,∣+i⟩⟨+i∣,12)(Y,|{+i}\rangle\langle{+i}|,\tfrac12)(Y,∣+i⟩⟨+i∣,21​), (Y,∣−i⟩⟨−i∣,−12)(Y,|{-i}\rangle\langle{-i}|,-\tfrac12)(Y,∣−i⟩⟨−i∣,−21​), (Z,∣0⟩⟨0∣,12)(Z,|0\rangle\langle0|,\tfrac12)(Z,∣0⟩⟨0∣,21​) and (Z,∣1⟩⟨1∣,−12)(Z,|1\rangle\langle1|,-\tfrac12)(Z,∣1⟩⟨1∣,−21​). For s=(se)∈[8]Ecuts=(s_e)\in[8]^{E_{\mathrm{cut}}}s=(se​)∈[8]Ecut​, the cut network (G′,As)(G',\mathcal A_s)(G′,As​) replaces every cut edge u→vu\to vu→v by u→▹(Ose)u\to\triangleright(O_{s_e})u→▹(Ose​​) and ◃(ρse)→v\triangleleft(\rho_{s_e})\to v◃(ρse​​)→v, and cs=∏ecsec_s=\prod_e c_{s_e}cs​=∏e​cse​​.

The estimator. For each sss, running the rrr pieces of (G′,As)(G',\mathcal A_s)(G′,As​) on the device yields an outcome ts∈[−1,1]t_s\in[-1,1]ts​∈[−1,1] whose expectation is T(G′,As)T(G',\mathcal A_s)T(G′,As​). One sample draws sss uniformly and outputs 8Kcsts8^Kc_st_s8Kcs​ts​. The estimate is the average of NNN independent samples.

Formalization targets

Goal: Theorem 1

For a (K,d)(K,d)(K,d)-clustered network with rrr clusters, any device laws as above and ε>0\varepsilon>0ε>0, let N=⌈4⋅24K/ε2⌉N=\lceil 4\cdot2^{4K}/\varepsilon^2\rceilN=⌈4⋅24K/ε2⌉. Then

Pr⁡[∣1N∑i=1N8Kcsitsi−T(G,A)∣<ε] ≥ 23.\Pr\Big[\Big|\tfrac1N\textstyle\sum_{i=1}^N 8^Kc_{s_i}t_{s_i}-T(G,\mathcal A)\Big|<\varepsilon\Big]\ \ge\ \tfrac23 .Pr[​N1​∑i=1N​8Kcsi​​tsi​​−T(G,A)​<ε] ≥ 32​.

Moreover, every cut network (G′,As)(G',\mathcal A_s)(G′,As​) splits into rrr clusters with no edges between them, each needing at most ddd qubits. Together, these give the paper's "O(24Kr/ε2)O(2^{4K}r/\varepsilon^2)O(24Kr/ε2) runs of a ddd-qubit device": NNN samples, each running rrr pieces.

Milestones, in the order the proof uses them

  • eq. (21): every 2×22\times22×2 matrix AAA equals ∑iciTr⁡(AOi)ρi\sum_i c_i\operatorname{Tr}(AO_i)\rho_i∑i​ci​Tr(AOi​)ρi​;
  • eqs. (27)–(28): ∑ici Oi⊗ρi=12(I⊗I+X⊗X+Y⊗Y+Z⊗Z)=SWAP\sum_i c_i\,O_i\otimes\rho_i=\tfrac12(I\otimes I+X\otimes X+Y\otimes Y+Z\otimes Z)=\mathrm{SWAP}∑i​ci​Oi​⊗ρi​=21​(I⊗I+X⊗X+Y⊗Y+Z⊗Z)=SWAP;
  • eqs. (23)–(30): αA(I)β=∑ici αA(Oi)A(ρi)β=δα,β{}_\alpha A(I)_\beta=\sum_i c_i\,{}_\alpha A(O_i)A(\rho_i)_\beta=\delta_{\alpha,\beta}α​A(I)β​=∑i​ci​α​A(Oi​)A(ρi​)β​=δα,β​;
  • Lemma 1: T(G,A)=∑i=18ciT(G′,Ai)T(G,\mathcal A)=\sum_{i=1}^8c_iT(G',\mathcal A_i)T(G,A)=∑i=18​ci​T(G′,Ai​) for one cut edge, with ci=±12c_i=\pm\tfrac12ci​=±21​, ρi\rho_iρi​ states and OiO_iOi​ Pauli observables with Oiρi=2ciρiO_i\rho_i=2c_i\rho_iOi​ρi​=2ci​ρi​;
  • eqs. (31)–(32): T(G,A)=∑scsT(G′,As)T(G,\mathcal A)=\sum_{s}c_sT(G',\mathcal A_s)T(G,A)=∑s​cs​T(G′,As​) for any set of cut edges;
  • eq. (33): T(G,A)=Es[8KcsT(G′,As)]T(G,\mathcal A)=\mathbb E_s[8^Kc_sT(G',\mathcal A_s)]T(G,A)=Es​[8Kcs​T(G′,As​)], and ∣cs∣=2−K|c_s|=2^{-K}∣cs​∣=2−K;
  • Hoeffding's inequality in the paper's form, Pr⁡[∣Xˉ−EXˉ∣<δ]≥1−2e−Nδ2/2a2>2/3\Pr[|\bar X-\mathbb E\bar X|<\delta]\ge1-2e^{-N\delta^2/2a^2}>2/3Pr[∣Xˉ−EXˉ∣<δ]≥1−2e−Nδ2/2a2>2/3 for N≥4a2/δ2N\ge4a^2/\delta^2N≥4a2/δ2;
  • the pieces claim: every cut network falls into rrr pieces of at most ddd qubits;
  • eqs. (35)–(36): one sample is unbiased for T(G,A)T(G,\mathcal A)T(G,A) and bounded by a=22Ka=2^{2K}a=22K.

Significance

The theorem turns the qubit budget of a device into a parameter of the simulation: a circuit on nnn qubits can be run on d<nd<nd<n qubits at a cost of 2O(K)2^{O(K)}2O(K), which is efficient whenever only K=O(log⁡n)K=O(\log n)K=O(logn) qubits pass between clusters. Its edge-cutting identity (Lemma 1) is the basic quasi-probability decomposition of the identity channel. It is reused in the paper's own Theorem 2 (decomposable post-processing, contraction-complexity bounds) and in its Hamiltonian-simulation application.

The theorem has a complete proof with explicit constants on pp. 8–10 of the paper. No machine-checked proof of the theorem or of its edge-cutting lemma is known. Formalizing it gives a machine-checked tensor-network semantics for the cut, the Pauli measure-and-prepare decomposition, and a concrete Monte Carlo guarantee. The general two-sided Hoeffding bound is already proved on the platform (Concentration.hoeffding_two_sided) and is included as a reference.

Difficulty

The decomposition of the identity channel is a finite matrix identity. The difficulty is in carrying it through the network. Cutting KKK edges at once changes the vertex and edge types of the graph, and the sum over ΠE\Pi^{E}ΠE must be re-indexed over the new edge set. The obvious route, cutting one edge at a time, changes the type of the graph at every step and does not compose cleanly. The statement is therefore made for a set of edges at once.

A second difficulty is probabilistic. The samples are drawn from a mixture over 8K8^K8K strings of pushforwards of device laws. Applying Hoeffding's inequality requires the product law of NNN such samples, a bound on their support, and the identification of their mean with the complex value T(G,A)T(G,\mathcal A)T(G,A).

Formalization scope

  • Edge indices are Fin 2 × Fin 2. Single-qubit operators are Matrix (Fin 2) (Fin 2) ℂ. The eight cases are Fin 8, and Lean's iii is the paper's i+1i+1i+1.
  • A network has finite vertex and edge types, src tgt : E → V, and tensors A : V → (E → Π) → ℂ that read a full edge labelling. Locality is not imposed, so all statements hold for slightly more general networks than the paper's. Vertex kinds are not recorded: a ◁ is a vertex without incoming edges.
  • The cut for a set CCC has vertices V⊕(C⊕C)V\oplus(C\oplus C)V⊕(C⊕C) and edges E⊕CE\oplus CE⊕C. The observable ▷ sits on the source side of the edge and reads the original edge. The state ◁ sits on the target side and feeds the target through the new edge. Only the target vertex is rerouted.
  • Clusters are labels in Fin r, and empty clusters are allowed. The qubit count is d(Si)=d(S_i)=d(Si​)= #◁ plus the incoming cut edges. This is the paper's p. 3 form; the paper's "out-degree" phrasing on p. 2 is not used.
  • The device is modelled only by its laws: for each sss, a probability measure on R\mathbb RR, almost surely in [−1,1][-1,1][−1,1], with mean T(G′,As)T(G',\mathcal A_s)T(G′,As​). This is p. 10's "Note that", taken as a hypothesis. Eq. (10), T(G,A)=Eyf(y)T(G,\mathcal A)=\mathbb E_yf(y)T(G,A)=Ey​f(y), is cited in the paper and not formalized. The run-time clause O(24K(n+m)/ε2)O(2^{4K}(n+m)/\varepsilon^2)O(24K(n+m)/ε2) is not formalized (there is no cost model).
  • NNN is the paper's 4a2/ε24a^2/\varepsilon^24a2/ε2 with a=22Ka=2^{2K}a=22K, rounded up. The NNN samples are the coordinates of the NNN-fold product of the one-sample law. The real estimate is compared with the complex T(G,A)T(G,\mathcal A)T(G,A) in C\mathbb CC; no real part is taken.
  • Corrections. Eq. (24) cites Eq. (7) for the identity-gate tensor where Eq. (6) is meant; the identity is formalized with (6). Lemma 1's existential "there is a set of eight coefficients …" is stated for the paper's own data, with "valid quantum circuit" pinned down as: ρi\rho_iρi​ positive semidefinite, trace one and idempotent; OiO_iOi​ Hermitian with Oi2=IO_i^2=IOi2​=I; and Oiρi=2ciρiO_i\rho_i=2c_i\rho_iOi​ρi​=2ci​ρi​.
  • Ruled out. The cut network is constructed from (G,A)(G,\mathcal A)(G,A), EcutE_{\mathrm{cut}}Ecut​ and sss, not assumed. The device laws have mean T(G′,As)T(G',\mathcal A_s)T(G′,As​), not T(G,A)T(G,\mathcal A)T(G,A). NNN is explicit, not "some NNN". The ddd-qubit claim is part of the goal.
  • Reusable beyond this mission: the tensor-network value, the edge cut and the Pauli measure-and-prepare data. Contributions of general lemmas on re-indexing sums over ΠE⊕C\Pi^{E\oplus C}ΠE⊕C are welcome.

Selected references

  • T. Peng, A. W. Harrow, M. Ozols, X. Wu, Simulating Large Quantum Circuits on a Small Quantum Computer, arXiv:1904.00102v2 (2020); Phys. Rev. Lett. 125, 150504 (2020). https://arxiv.org/abs/1904.00102
  • S. Bravyi, G. Smith, J. A. Smolin, Trading Classical and Quantum Computational Resources, Phys. Rev. X 6, 021043 (2016). https://doi.org/10.1103/PhysRevX.6.021043
  • W. Hoeffding, Probability Inequalities for Sums of Bounded Random Variables, J. Amer. Statist. Assoc. 58, 13–30 (1963). https://doi.org/10.1080/01621459.1963.10500830
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Discrete Geometry·Captain: Lucas

The moving sofa problem: optimality of Gerver's sofaResearch Paper

Motivation

The moving sofa problem, posed by Leo Moser in 1966, asks for the planar shape of largest area that can be moved around a right-angled corner in a hallway of unit width — one of the most famous unsolved problems of everyday geometry. Joseph Gerver exhibited in 1992 a sofa of area 2.2195... built from five boundary curves solving a system of balancing ordinary differential equations, and conjectured it to be the largest possible; Dan Romik later derived the curves' exact formulas, and Kallus and Romik proved the best upper bound before the source. The source resolves the problem: Baek proves that Gerver's sofa is optimal, so the sofa constant is Gerver's area 2.2195..., and the sixty-year-old problem is closed.

The mission formalizes the proof of Theorem 1.1.1 of the source — Gerver's sofa attains the maximum area among all moving sofas — following the paper's own attack path: reduce to monotone sofas and their supporting rotation paths, express the sofa area through the cap and niche of the path, control the rotation angle of large sofas, take Hausdorff limits of maximum polygon sofas to obtain balanced maxima, establish the injectivity of the supporting path of a maximizer, and dominate every injectivity-constrained path by a Gerver sofa through the concavity of the area upper bound Q.

The fragment and its conventions

The arena is the L-shaped hallway L, the union of the horizontal side (-∞, 1] × [0, 1] and the vertical side [0, 1] × (-∞, 1]. A shape is a nonempty compact subset of the plane — the source's standing convention, adopted here — and a moving sofa is a nonempty, compact, connected shape that admits a movement around the corner. A movement is encoded by two continuous paths: a rotation angle path Θ and a translation path W, producing the rigid motion Φ_t(p) = rot(Θ t) p + W t of the unit interval, with Θ 0 = 0, the initial image inside the horizontal side, every intermediate image inside the hallway, the final image inside the vertical side, and total clockwise rotation -Θ 1 = ω, the movement's rotation angle. The area of a planar set is its two-dimensional Lebesgue measure as a real number; the maximum sofa area α_max is the supremum of the areas of all moving sofas.

The monotone arena replaces sofas by their supporting rotation paths. A rotation path x with angle ω ∈ (0, π/2] determines strips, quarter-planes Q_t⁺ \ Q_t⁻ at the outer and inner corners of the translated hallways, the parallelogram P_ω, the fan F_ω, the cap (Equation 1.3), the niche (Equation 1.4), and the monotone sofa of the path — the common part of the strips and the hallways (Equation 1.2). A supporting path pins down the canonical inner-corner path through contact: both outer walls of every supporting hallway touch the sofa. Balanced maximum sofas are stated at the level of sofas: a moving sofa that is the Hausdorff limit of maximum polygon sofas whose uniform angle sets run over a strictly increasing sequence of powers of two, with Hausdorff convergence phrased through Euclidean ε-neighborhoods rather than Mathlib's metric thickening API. The Gerver sofa is characterized by the paper's own structural properties: a moving sofa equal to the monotone sofa of its rotation path, whose supporting-hallway structure is carried by the five curves of Definition 8.4.3 with contact on the outer and inner walls and satisfying the balancing ODEs of Theorem 8.4.2 on the five intervals cut by angles 0 < φ < θ < π/4, derivatives taken one-sided within each interval. The source defers the curves' explicit formulas to Gerver's and Romik's papers; the existential form — some sofa satisfying this structure — is used for the goal and the dominating bound, since that is what the proof of Theorem 1.1.1 actually produces.

Six conventions deserve disclosure. First, the platform publishes definitions as modules Definitions.Def_<definition_name>, so the three definition bundles — the hallway arena, the monotone arena, and the Gerver sofa structure with Mamikon's swept region — are published as platform definitions (Gerver_arena, Gerver_monotone, Gerver_sofa) and attached to the proposal as reference items; the theorem drafts import them. Second, the injectivity condition abridges the source's Definition 6.1.2 by dropping its auxiliary clause on the boundary curve σ_K, keeping the continuous differentiability and the two strict derivative inequalities that the endgame consumes. Third, balancedness is stated at the sofa level rather than through the paper's rotation-path data, the sofa-level form being what the compactness argument yields. Fourth, the generalized Mamikon theorem is stated for continuously differentiable tangent segment families with continuous lengths and pairwise non-overlap on the open parameter rectangle, over turning intervals of length below π — exactly the smooth, non-self-overlapping families to which the endgame applies it. Fifth, the movement's initial term is a pure translation (Θ 0 = 0), matching the source's Definition 1.1.2 with its footnote. Sixth, all statements are developed against the platform's Mathlib build (0df444a), with inner products, rotations, scalings, and neighborhoods given by small self-contained definitions so that every draft compiles without instance-hunting.

Formalization targets

The goal is Theorem 1.1.1: some Gerver sofa has area at least that of every moving sofa. The supporting chain, in the paper's order, each step a milestone except the last:

  • Monotone reduction: every moving sofa is contained in a monotone moving sofa of at least its area — the intersection of the supporting hallways.
  • Cap-niche identity: a moving monotone sofa is its cap minus its niche.
  • Area functional: the sofa area is the cap area minus the niche area whenever the niche lies in the cap.
  • Angle control: a moving sofa of area at least 2.2 admits a movement of rotation angle in [arccos(1/2.2), π/2].
  • Balanced maxima: for each rotation angle, a balanced maximum sofa exists as the Hausdorff limit of maximum polygon sofas.
  • Right-angle reduction: a balanced maximum sofa of large area has a rotated copy admitting a movement of angle π/2.
  • Injectivity: the supporting rotation path of a maximum-area balanced sofa of angle π/2 satisfies the injectivity condition.
  • Mamikon: the area swept by a smooth non-overlapping tangent segment family is half the integral of the squared lengths.
  • Dominating bound: some Gerver sofa bounds the area of every monotone sofa of an injectivity-constrained supporting path of angle π/2.

The goal follows by assembling the chain: every moving sofa sits under a monotone one, maximizers are balanced maxima admitting the full right angle, their supporting paths are injectivity-constrained, and the dominating bound caps them by a Gerver sofa.

Significance

The moving sofa problem is a benchmark of planar geometry that has resisted exact solution since 1966; the source closes it. The proof is not a computational verification but a structural argument — compactness produces extremal objects, contact geometry pins their supporting paths, injectivity rules out self-overlap, and a concavity argument of a kind familiar from calculus of variations delivers the dominating bound. Each layer is a theorem of lasting value independently of the goal: the cap-niche decomposition, the existence of balanced maxima, the injectivity of maximizer paths, and the generalized Mamikon theorem all predate or outlive the final step. A Lean formalization makes each layer independently checkable, and the mission's chain structure lets solvers claim credit for any layer while the community assembles the whole.

Difficulty

The formalization spans real analysis, topology, convex geometry, and measure theory, at a level well beyond elementary competition material but below the frontier of ongoing formalization projects. The monotone reduction and the cap-niche identity require careful handling of intersections of translated half-planes and the additivity of Lebesgue measure; the balanced-maximum existence requires sequential compactness in the Hausdorff topology; injectivity requires differentiability arguments on paths defined by contact conditions; the endgame requires the concavity of the functional Q on triples of convex bodies. The definitions are engineered to be self-contained — plain real arithmetic for inner products, rotations, and neighborhoods — so that the labor concentrates on the geometry rather than on API friction. Individual milestones are of moderate difficulty; the goal requires assembling all of them, which is the source's own achievement.

Formalization scope

Every item quantifies only over the objects it needs — hallways, shapes, rotation paths, angle sets, segment families; no item carries a vacuous hypothesis: moving sofas, monotone sofas, polygon intersections, and Gerver sofas all exist, and the inequalities are in the intended directions. The fragment excludes the explicit trigonometric formulas of Gerver's curves (the goal needs only their structural characterization), the source's sections on the ambidextrous sofa and non-convex generalizations, the computer-search evidence for the sofa constant's decimals, and any statement about shapes that are not moving sofas. Nothing in the mission asserts the uniqueness of the Gerver sofa or the value of the sofa constant as a decimal; it formalizes what the source proves — optimality.

Selected references

  • J. Baek, Optimality of Gerver's Sofa, arXiv:2411.19826 (2024) — the mission's source.
  • L. Moser, Problem 66-11, Moving Furniture Through a Hallway, SIAM Review 8 (1966), p. 381 — the problem.
  • J. L. Gerver, On Moving a Sofa around a Corner, Geometriae Dedicata 42 (1992), pp. 267–283 — the sofa and the balancing ODEs.
  • D. Romik, Differential Equations and Exact Solutions in the Moving Sofa Problem, Experimental Mathematics 27 (2018), pp. 316–330 — the curves' exact formulas.
  • Y. Kallus and D. Romik, Improved Upper Bounds in the Moving Sofa Problem, Advances in Mathematics 340 (2018), pp. 960–982 — the preceding upper bound.
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Algorithmic Game TheoryMarkov ChainOperations Research·Captain: mikedeng1

Shapley Meets Uniform: An Axiomatic Framework for Attribution in Online Advertising: In the Markov Chain Model, CASV Equals Unique-Uniform Attribution Minus Its CounterfactualResearch Paper

Why this attribution problem arises

An advertiser observes customer paths through a sequence of states and advertising actions, then wants to assign credit for a purchase to the actions that occurred. Giving the last action all the credit misses earlier interactions; dividing credit by the number of visits can overreward a repeated action. Credit should also reflect what would have happened under the baseline no-ad action. Singal, Besbes, Desir, Goyal, and Iyengar formulate these requirements in a Markov model and a cooperative game, then connect their counterfactual adjusted Shapley value to a path-based quantity (Singal et al., SSRN version, §§3–5).

The paper is a known research result, published in Management Science in 2022. This mission uses the authors' August 21, 2021 SSRN version, whose displayed equations and page numbers are the formalization's citation basis. Its objective is to formalize the paper's characterization theorem, together with the intermediate claims that identify what a coalition is worth and how the ordinary Shapley value treats a converting customer path.

Markov chains, coalitions, and converting paths

The transient states are S={1,…,m}\mathbb S=\{1,\ldots,m\}S={1,…,m}; a customer eventually reaches either the absorbing conversion state ccc or the absorbing quit state qqq. The actions are A={1,…,n}\mathbb A=\{1,\ldots,n\}A={1,…,n}, with action 111 designated as the baseline no-ad action. A customer begins at state sss with probability λs\lambda_sλs​. At state sss, the advertiser takes action aaa with probability βsa\beta_s^aβsa​. The probabilities pss′ap^a_{ss'}pss′a​, pscap^a_{sc}psca​, and psqap^a_{sq}psqa​ govern the next transient state, conversion, and quitting. The initial and action distributions sum to one, each transition row sums to one, and all probabilities are nonnegative. The paper's absorption assumption says that every customer eventually converts or quits, starting from any transient state (§2.1, pp. 6–8).

A player is one state-action pair r=(s,a)r=(s,a)r=(s,a), and the player set is P=S×A\mathbb P=\mathbb S\times\mathbb AP=S×A. To value a coalition X⊆PX\subseteq\mathbb PX⊆P, only its players keep their actions. Action probability assigned to a pair outside XXX instead takes an artificial zero-value action that sends the customer to qqq. If PXP^XPX is the resulting transient-state transition matrix and pcXp_c^XpcX​ its one-step conversion vector, the coalition value is the conversion probability v(X)=λ⊤(I−PX)−1pcXv(X)=\lambda^\top(I-P^X)^{-1}p_c^Xv(X)=λ⊤(I−PX)−1pcX​. Conversion has value one, so there is no additional revenue parameter (§2.3, p. 9; §4.2, pp. 14–15).

The Shapley value πrShap\pi_r^{\mathrm{Shap}}πrShap​ averages the marginal value v(X∪{r})−v(X)v(X\cup\{r\})-v(X)v(X∪{r})−v(X) over coalitions XXX that omit rrr, weighted by ∣X∣!(mn−∣X∣−1)!/(mn)!|X|!(mn-|X|-1)!/(mn)!∣X∣!(mn−∣X∣−1)!/(mn)!. For the counterfactual adjusted Shapley value, or CASV, the baseline value is instead v(X∪{(s,1)a})v(X\cup\{(s,1)^a\})v(X∪{(s,1)a}): the frequency βsa\beta_s^aβsa​ assigned to rrr is spent on the no-ad transition row, in addition to any existing no-ad frequency. Thus CASV compares an advertising action with its specified no-ad alternative (§4.2–4.3, pp. 15–16).

A path P\mathcal PP lists the state-action pairs encountered before quitting or conversion. Write u(P)u(\mathcal P)u(P) for the number of distinct pairs, regardless of repetitions. The unique-uniform weight wr(P)w_r(\mathcal P)wr​(P) is 1/u(P)1/u(\mathcal P)1/u(P) when the path converts and contains rrr, and zero otherwise. It rewards each distinct participating pair once (§3.3, p. 12; Proposition 1, p. 20).

Formalization targets

The first target is Proposition 1, which identifies the ordinary Shapley value of the coalition game with the expected unique-uniform weight:

πrShap(M)=EP∼M[wr(P)].\pi_r^{\mathrm{Shap}}(\mathcal M)=\mathbb E_{\mathcal P\sim\mathcal M}[w_r(\mathcal P)].πrShap​(M)=EP∼M​[wr​(P)].

The mission goal is Theorem 2. Let Mr\mathcal M_rMr​ be the counterfactual chain for rrr. It characterizes CASV as a difference of two path expectations:

ψrShap(M)=EP∼M[wr(P)]−EP∼Mr[wr(P)].\psi_r^{\mathrm{Shap}}(\mathcal M)=\mathbb E_{\mathcal P\sim\mathcal M}[w_r(\mathcal P)]-\mathbb E_{\mathcal P\sim\mathcal M_r}[w_r(\mathcal P)].ψrShap​(M)=EP∼M​[wr​(P)]−EP∼Mr​​[wr​(P)].

The milestone list also records display (6), the matrix and path forms of coalition value in Step 1 of the proof of Proposition 1, and the Step 3 carrier-game identity. These are the paper's intermediate statements, with the carrier-game fact linked to an already proved general Shapley theorem (pp. 16, 20–22).

What the characterization provides

Theorem 2 gives a path-based meaning to a value defined by averaging over coalitions. It separates the credit earned in the observed Markov chain from the credit that the same player identity would earn under a baseline no-ad transition. This distinction matters in the paper's Example 5: an ad and a no-ad action both guarantee conversion, so the ad receives zero counterfactual credit despite having ordinary Shapley value one (pp. 15–16, 20, 22).

The paper also develops estimation methods after the characterization, but those algorithms and their numerical performance are outside this mission. Formalizing the known theorem would supply a reusable connection among absorbing finite chains, coalition conversion games, and Shapley values. The linked general Shapley definition and carrier-game result are already available as platform content; the paper-specific model and theorem statements here remain draft formalization targets.

Where the mathematical difficulty lies

A coalition changes which state-action pairs can contribute to a path. The Shapley definition averages marginal coalition values, whereas a path expectation assigns a weight to a realized sequence, including sequences that revisit the same pair. Identifying these two descriptions requires accounting for the distinct set of players on every converting path. Counterfactual adjustment adds another chain whose player identities and action frequencies must align with the original model; simply removing or merging the player changes the quantity in Theorem 2 (proof of Proposition 1, p. 21; Appendix B, p. 46).

Formalization scope and conventions

States and actions are Fin m and Fin n, so the paper's index kkk is Lean index k−1k-1k−1. The model designates a noAd action rather than assuming it is Lean index zero. Players are pairs in Fin m × Fin n; the ordinary Shapley value transports them to Fin (m*n) to reuse the published Shapley definition. The separate general action-chain definition contains the initial, action, and transition probabilities; the attribution model adds the no-ad action and the coalition game.

The Valid predicate states every distribution and row-sum condition. Absorbing states convergence of powers of the original averaged transient matrix to zero. Theorem 2 additionally assumes absorption of the counterfactual chain, because absorption of the original alone does not imply it. This makes the inverse in each coalition value represent the conversion probability under the paper's Assumption 1; a singular matrix's totalized Lean inverse must not supply a default answer.

The counterfactual chain keeps rrr at frequency βsa\beta_s^aβsa​ and as a player, while replacing its transition row by the no-ad row. This reading matches the counterfactual marginal displayed in Appendix B. Pairs outside a coalition take the artificial quit action; that action is never a player. Path expectation is a real tsum over finite converting paths, each weighted by its initial probability, action frequencies, transitions, and final conversion probability. Nonconverting paths contribute zero. The Shapley weight and the conversion value one are exactly the paper's constants. CASV is defined by display (5), and path expectation is defined independently, so Theorem 2 does not follow by unfolding a prearranged identity. Work on path summability, matrix-series convergence, coalition path expansions, and the connection to the general Shapley theorem is welcome.

Selected references

  • R. Singal, O. Besbes, A. Desir, V. Goyal, and G. Iyengar, Shapley Meets Uniform: An Axiomatic Framework for Attribution in Online Advertising, Management Science 68 (2022). Authors' SSRN version of August 21, 2021; journal DOI.
  • L. S. Shapley, A Value for n-Person Games, in Contributions to the Theory of Games II, Princeton University Press, 1953. DOI.
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Algorithmic Game TheoryEconomicsOperations Research·Captain: mikedeng1

Optimal Duration of Innovation Contests: For a Patient Organizer, the Optimal Contest Duration Increases with the Scale of the Agent Uncertainty and Decreases with the Productivity ExponentResearch Paper

Motivation

An innovation contest gives several agents a fixed period to submit solutions and awards prizes according to their final ranks. A platform choosing that period faces two practical effects: more time lets agents improve their submissions, while it delays the value of the best solution and can make the effort needed to participate more costly overall. The question is how the chosen duration changes when the quality of submissions becomes more uncertain or when agents become more productive over time. Korpeoglu, Körpeoğlu, and Tunç study this decision in a contest model motivated by crowdsourcing platforms and distinguish organizers by how strongly they discount a late solution. Their patient organizer result is the target here. Korpeoglu, Körpeoğlu, and Tunç, 2020.

Setting

There are N≥2N\ge2N≥2 agents and a fixed present-value award scheme. Agent iii chooses a nonnegative per-time effort path ηi(t)\eta_i(t)ηi​(t) during a contest of duration T>0T>0T>0. The path improves deterministic output at rate θ(t)ηi(t)\theta(t)\eta_i(t)θ(t)ηi​(t), where productivity θ(t)\theta(t)θ(t) is positive. The final output adds an independent random shock ξ~i\tilde\xi_iξ~​i​ with a common mean-zero, log-concave density hhh. The organizer values the best final output. The model uses the scale transformation αξ~i\alpha\tilde\xi_iαξ~​i​ to vary uncertainty without choosing a special distribution; its density is hα(s)=h(s/α)/αh_\alpha(s)=h(s/\alpha)/\alphahα​(s)=h(s/α)/α for α>0\alpha>0α>0. When studying changing productivity, the paper sets θ(t)=exp⁡(ρt)\theta(t)=\exp(\rho t)θ(t)=exp(ρt), so ρ\rhoρ is the productivity exponent. Model, pp. 8–9.

Effort costs cηi(t)bc\eta_i(t)^bcηi​(t)b per unit time, with c>0c>0c>0 and b>1b>1b>1. Write ei=∫0Tθ(t)ηi(t) dte_i=\int_0^T\theta(t)\eta_i(t)\,dtei​=∫0T​θ(t)ηi​(t)dt for total deterministic output improvement. The least cost of producing eie_iei​ is ψ(ei,T)=ceibτ(T)1−b\psi(e_i,T)=c e_i^b\tau(T)^{1-b}ψ(ei​,T)=ceib​τ(T)1−b, where τ(T)=∫0Tθ(t)b/(b−1) dt\tau(T)=\int_0^T\theta(t)^{b/(b-1)}\,dtτ(T)=∫0T​θ(t)b/(b−1)dt. A participant also bears a fixed cost F>0F>0F>0. An agent with the jjjth-largest output receives a present-value award A(j)=Aγ(j)A(j)=A\gamma(j)A(j)=Aγ(j), with A>0A>0A>0, nonnegative, nonincreasing shares γ(j)\gamma(j)γ(j), and ∑j=1Nγ(j)=1\sum_{j=1}^N\gamma(j)=1∑j=1N​γ(j)=1. The contest's symmetric equilibrium effort is represented by e∗(T)=(Ax/(cb))1/(b−1)τ(T)e^*(T)=(Ax/(cb))^{1/(b-1)}\tau(T)e∗(T)=(Ax/(cb))1/(b−1)τ(T), where x=∑j=1NIjNγ(j)x=\sum_{j=1}^N I_j^N\gamma(j)x=∑j=1N​IjN​γ(j) and IjNI_j^NIjN​ measures the effect of a small effort increase on the probability of rank jjj. Lemma 1 and equations (3)–(5), pp. 10–12.

For this mission the award scheme is held fixed, as it is in the paper's duration analysis. The organizer chooses among positive durations satisfying the agents' best-response and participation conditions. At duration TTT, the organizer's profit is Π(T)=e−δT(e∗(T)+E[ξ~(1)N])−A\Pi(T)=e^{-\delta T}(e^*(T)+E[\tilde\xi^N_{(1)}])-AΠ(T)=e−δT(e∗(T)+E[ξ~​(1)N​])−A, where δ≥0\delta\ge0δ≥0 is the organizer's discount factor and ξ~(1)N\tilde\xi^N_{(1)}ξ~​(1)N​ is the largest shock. An optimal duration maximizes this profit among feasible durations. The patient regime is δ<δ1\delta<\delta_1δ<δ1​, with δ1\delta_1δ1​ evaluated from the model at the solution Tˉ\bar TTˉ of the participation equation (9). The paper's footnote 11 requires the agent's best-response condition to hold at Tˉ\bar TTˉ for that duration to be available. Equations (6)–(9) and footnote 11, pp. 12–13; threshold, p. 27.

Formalization targets

The goal is Theorem 1's pair of comparative statics. For each parameter value satisfying the patient regime and the stated regularity assumptions, let T∗T^*T∗ be the unique optimal feasible duration. Holding the productivity function and award scheme fixed, the uncertainty-scale target is

0<α1<α2⟹T∗(α1)<T∗(α2).0<\alpha_1<\alpha_2\quad\Longrightarrow\quad T^*(\alpha_1)<T^*(\alpha_2).0<α1​<α2​⟹T∗(α1​)<T∗(α2​).

With uncertainty normalized to its unscaled distribution and productivity θ(t)=eρt\theta(t)=e^{\rho t}θ(t)=eρt, the productivity target is

ρ1<ρ2⟹T∗(ρ2)<T∗(ρ1).\rho_1<\rho_2\quad\Longrightarrow\quad T^*(\rho_2)<T^*(\rho_1).ρ1​<ρ2​⟹T∗(ρ2​)<T∗(ρ1​).

The regime is checked at both values in each comparison, since δ1\delta_1δ1​ itself changes with the density or productivity. The milestone statements cover optimal effort allocation, the equilibrium effort formula, the patient case of Lemma 2, the scale identities for the expected maximum and rank incentives, and the duration expression under exponential productivity. Theorem 1, p. 14; proof, p. 27.

Significance

The result links the contest's deadline to two distinct features of the agents' work. Greater output uncertainty changes the return to effort, while a larger productivity exponent changes when effort is most effective. For a patient organizer, the paper concludes that the first change lengthens the selected contest and the second shortens it. The statements concern an actual maximizer of profit under participation, so they can inform a duration decision for a specified award scheme, rather than merely compare algebraic expressions. Discussion of Theorem 1, pp. 14–15.

The paper proves these results mathematically. This mission supplies compiled Lean declarations for the model and its main claims; their theorem proofs remain open. A completed development would give machine-checked versions of the fixed-award, patient-organizer conclusions and reusable definitions for real shock densities, scaling, order statistics, effort allocation, and constrained duration optimization. It would also make the assumptions behind the paper's comparative statics visible in one interface.

Difficulty

The organizer cannot choose duration by looking only at the direct effect of more time on output. Longer contests alter equilibrium effort and agent costs, which changes participation, while discounting changes the value of the best output. The organizer therefore maximizes profit over a feasible set whose boundary depends on the same effort response. Identifying the patient regime requires the threshold δ1\delta_1δ1​ from the proof of Lemma 2. Under shock scaling, the expected maximum and the rank-incentive coefficient transform differently; both must be accounted for in the same optimization problem. For negative ρ\rhoρ, the integral τ(T)\tau(T)τ(T) can have a finite upper bound, so the participation equation need not have a positive solution. Lemma 2, p. 13; proof of Theorem 1, p. 27.

Formalization scope

The Lean representation uses real-valued densities and integrals, natural-number ranks 1,…,N1,\ldots,N1,…,N, real powers on positive bases, and a positive-duration feasible domain. The standing model has N≥2N\ge2N≥2, b>1b>1b>1, c>0c>0c>0, F>0F>0F>0, 0<A0<A0<A, F<A/NF<A/NF<A/N, δ≥0\delta\ge0δ≥0, ordered nonnegative award shares summing to one, a continuous positive productivity function, and a mean-zero log-concave shock density. Published CrowdContest.Pooling.Density supplies the general density, CDF, and expected-maximum operations; its symmetric-shock condition is not used. Published ConvexOptimization.LogConcaveOn supplies log-concavity. The paper's stated assumptions that profit is unimodal and has a positive derivative at zero are explicit; unimodality is read as strict increase throughout or strict increase followed by strict decrease. The added condition x>0x>0x>0 excludes equal awards, for which the paper's cited auxiliary lemma supplies only x≥0x\ge0x≥0. A positive solution Tˉ\bar TTˉ to equation (9) is required; this avoids assigning meaning to a missing inverse or a nonpositive logarithm argument. The agent's best-response condition at Tˉ\bar TTˉ is required, matching footnote 11 on p. 13.

An optimal duration is defined by maximization of the paper's profit (6) under the best-response condition (7) and participation (8). It is not defined to equal Tˉ\bar TTˉ or the logarithmic expression: that characterization is theorem content. The effort inserted into profit is equation (5), as in the paper's reduction; a rank-probability integral states what it means for that effort to solve (7). The open development needs results about interval integrals, real powers, log-concave density moments, the change of variables under scaling, best responses, and maximization under the participation constraint. The impatient case of Lemma 2 and later award-design results are outside this mission.

Selected references

  • C. G. Korpeoglu, E. Körpeoğlu, and S. Tunç, Optimal Duration of Innovation Contests, authors' SSRN version, forthcoming at Manufacturing & Service Operations Management, 2020. SSRN 3064763.
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Ad Blocking: Total Consumer Surplus Is Lower with an Adblocker When Consumers Are Heterogeneous Enough in Ad or Quality Sensitivity, and Higher Only When Both Are Nearly HomogeneousResearch Paper

Motivation

Advertising pays for content that many readers receive without a direct subscription charge. An adblocker changes two parts of that arrangement: some readers see fewer ads, and the publisher may earn less from investing in content quality. Readers can benefit from the first change and lose from the second. A comparison of consumer surplus therefore has to account for the publisher's response, rather than hold quality fixed. Gritckevich, Katona, and Sarvary's Ad Blocking studies this question in a game where an adblocker can also obtain a payment from the publisher by threatening to block all ads for its users.

The paper's Proposition 3 says that the direction of the consumer-surplus comparison depends on heterogeneity in readers' sensitivity to advertising and content quality. It provides a reason why a tool that visibly removes an annoyance need not raise the total surplus of its users and other readers once the content market adjusts. The result is relevant to people assessing ad-supported publishing and adblocker policies, especially when a partial-blocking tool and its publisher payment are part of the business model.

Setting

One publisher chooses content quality q≥0q\ge0q≥0 at cost cq2cq^2cq2, where c>0c>0c>0, and earns a positive price pap_apa​ for each advertising impression. The publisher later chooses advertising volume A≥0A\ge0A≥0. A unit mass of consumers differs in three independent characteristics. Their quality sensitivity ϑ\varthetaϑ is uniform on [t,1][t,1][t,1], their ad sensitivity γ\gammaγ is uniform on [r,1][r,1][r,1], and their cost κ\kappaκ of downloading an adblocker is uniform on [0,κˉ][0,\bar\kappa][0,κˉ]. The paper assumes 0≤t≤10\le t\le10≤t≤1, 0<r≤10<r\le10<r≤1, and that the upper download-cost bound κˉ\bar\kappaκˉ is large enough for its equilibrium analysis. At t=1t=1t=1 or r=1r=1r=1, the corresponding characteristic is constant.

Without an adblocker, a consumer's utility is max⁡{ϑq−γA,0}\max\{\vartheta q-\gamma A,0\}max{ϑq−γA,0}. A consumer visits when ϑq−γA≥0\vartheta q-\gamma A\ge0ϑq−γA≥0. With an adblocker available, the adblocker commits to a maximum ad volume V≥0V\ge0V≥0 for downloaders. A consumer who downloads pays κ\kappaκ and, in the equilibrium studied here, sees ad volume VVV. The resulting utility is

U=max⁡{ϑq−γA,  ϑq−γV−κ,  0}.U=\max\{\vartheta q-\gamma A,\;\vartheta q-\gamma V-\kappa,\;0\}.U=max{ϑq−γA,ϑq−γV−κ,0}.

The consumer downloads when the middle option strictly exceeds both alternatives. This tie convention affects only boundary consumers under a nondegenerate distribution, but it fixes a precise event for the formalization.

The adblocker sets VVV after quality is chosen. It can threaten to block all ads to its downloaders during negotiation with the publisher. In the paper's basic model, the publisher accepts an offer when indifferent, so the adblocker receives all advertising revenue generated by downloaders. The publisher's retained revenue comes from readers who do not download. The paper shows that, when κˉ\bar\kappaκˉ is large enough, the publisher's ad choice remains the benchmark-optimal AAA even with the adblocker. Equilibrium here means that AAA maximizes benchmark ad revenue at each quality, VVV maximizes the adblocker's payment at each quality, and quality maximizes the publisher's resulting profit.

Formalization targets

The goal is Proposition 3 of the paper. Write CSNACS_{NA}CSNA​ for expected total consumer utility without an adblocker and CSABCS_{AB}CSAB​ for expected total consumer utility with one, each evaluated at equilibrium. There are positive tolerances ε\varepsilonε and δ\deltaδ such that, for all sufficiently large κˉ\bar\kappaκˉ,

0<r<ε or 0≤t<ε⟹CSAB<CSNA,1−δ<r≤1 and 1−δ<t≤1⟹CSAB>CSNA.\begin{aligned} 0<r<\varepsilon\ \text{or}\ 0\le t<\varepsilon &\quad\Longrightarrow\quad CS_{AB}<CS_{NA},\\ 1-\delta<r\le1\ \text{and}\ 1-\delta<t\le1 &\quad\Longrightarrow\quad CS_{AB}>CS_{NA}. \end{aligned}0<r<ε or 0≤t<ε1−δ<r≤1 and 1−δ<t≤1​⟹CSAB​<CSNA​,⟹CSAB​>CSNA​.​

The tolerances are uniform over positive pap_apa​ and ccc. The point beyond which κˉ\bar\kappaκˉ is large enough may depend on pa,c,r,tp_a,c,r,tpa​,c,r,t. The inequalities apply to every equilibrium selection, so the target does not assume the paper's equilibrium formulas as inputs. The milestones, in attack order, are the benchmark optimum (Lemma 1), the download rule and the adblocker's payoff (6) at fixed quality, the adblocker's optimal limit (Proposition 1), the publisher's lost revenue (9), the publisher's quality response (Proposition 2), the fixed-quality consumer-surplus identity (11), the sign criterion used to compare the two regimes, and the strict inequality CΔ(r,0)<C0(r,0)G(r,0)C_\Delta(r,0)<C_0(r,0)G(r,0)CΔ​(r,0)<C0​(r,0)G(r,0) that settles the case t=0t=0t=0.

Boundary lines

On the two edges of the parameter square the paper gives exact thresholds: for all large κˉ\bar\kappaκˉ,

t=1: CSAB>CSNA  ⟺  r>141−114,r=1: CSAB>CSNA  ⟺  t>45,t=1:\ CS_{AB}>CS_{NA}\iff r>\tfrac{\sqrt{141}-1}{14},\qquad r=1:\ CS_{AB}>CS_{NA}\iff t>\tfrac45,t=1: CSAB​>CSNA​⟺r>14141​−1​,r=1: CSAB​>CSNA​⟺t>54​,

with CSAB<CSNACS_{AB}<CS_{NA}CSAB​<CSNA​ on the other side, threshold included. This is a sharper statement along the edges than the goal's "sufficiently high".

Significance

At fixed quality, downloaders can gain from seeing fewer ads, and the paper's surplus identity makes that gain positive. The equilibrium result determines when that gain outweighs the loss caused by lower publisher quality. Its low-heterogeneity region gives a precise setting in which total consumer surplus increases, while either sufficiently broad ad sensitivity or broad quality sensitivity makes the same intervention lower total consumer surplus. This is the distinction a fixed-quality comparison cannot make. The paper's separate total-welfare and extended bargaining results are not implied by this mission's goal.

A machine-checked development would connect an economic game's timing and best responses to explicit probability laws, integrals of consumer utility, and the resulting welfare comparison. The paper proves Proposition 3, but the Lean theorem and its supporting milestones are currently statements with open proofs. Completing them would also leave reusable formal components: a normalized interval law with point endpoints, a model of mixed discrete and continuous consumer types, and optimization statements for a staged publishing game. No machine-checked proof of this specific result is claimed here.

Difficulty

The immediate benefit to a downloader is easy to see only when the publisher's quality is held constant. That argument fails for total equilibrium consumer surplus because the adblocker captures downloader ad revenue, reducing the publisher's return to quality. The size of that quality response depends on the distribution of consumer sensitivities, while the direct benefit depends on who downloads and still consumes content. The case split at t=r/(1+r)t=r/(1+r)t=r/(1+r) changes the benchmark ad formula; the general fixed-quality gain has no simple closed form in the paper. The endpoint cases r=1r=1r=1 and t=1t=1t=1 also require genuine point-mass distributions rather than formulas that divide by 1−r1-r1−r or 1−t1-t1−t.

Formalization scope

Lean represents all prices, choices, utilities, and coefficients in R\mathbb RR. The three consumer characteristics have independent uniform laws, represented by iterated integrals. A point interval is represented by a Dirac law, preserving the source's r=1r=1r=1 and t=1t=1t=1 cases. Quality, ad volume, and the adblocker's limit are optimized over the nonnegative reals. Benchmark visits include a zero-utility tie; downloading requires a strict gain over both visiting without the tool and not visiting. The support bound κˉ\bar\kappaκˉ is positive and sufficiently large wherever the paper's calculations require it.

The base game uses the paper's equilibrium convention that the publisher retains the benchmark-optimal ad volume with the adblocker present. Negotiation is represented in reduced form: the adblocker receives the entire ad revenue from downloaders, and the publisher keeps revenue from other visitors. Positivity of the ad price and quality-cost coefficient, implicit in the economic setup, is explicit in Lean. The source's phrase “κ\kappaκ high enough” in Proposition 3 is read as “κˉ\bar\kappaκˉ high enough,” since κ\kappaκ is an individual's cost and κˉ\bar\kappaκˉ sets its population range. A corrected normalization factor in the printed first branch of C0C_0C0​ is recorded in the definition and moderation notes. Closed-form milestones such as (6) and (9) carry an explicit lower bound on κˉ\bar\kappaκˉ, namely the upper limit of the paper's κ\kappaκ-integral. The paper's weak inequality CΔ(r,0)≤C0(r,0)G(r,0)C_\Delta(r,0)\le C_0(r,0)G(r,0)CΔ​(r,0)≤C0​(r,0)G(r,0) is stated strictly, which is true on (0,1](0,1](0,1] and is what the goal needs.

The goal uses expected utility and best-response conditions, not values manufactured from the closed-form formulas. A proof therefore must establish that the modeled equilibria exist and satisfy the paper's formulas; otherwise a universal comparison over an empty set of equilibria would have no economic content. Contributions that prove the interval-law facts, measurable and integrable consumer events, benchmark and adblocker best responses, or the sign criterion all advance the same target.

Selected references

  • Alexander Gritckevich, Zsolt Katona, and Miklos Sarvary, Ad Blocking, SSRN preprint 3100524, version of March 7, 2021; published in Management Science, 2021. SSRN preprint; journal DOI.
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EconomicsOperations Research·Captain: mikedeng1

Resource Allocation Among Competing Innovators: Optimal Allocation Between Investing in One and Investing in Two InnovatorsResearch Paper

Why allocate resources before innovation?

Research funders and investors choose how many innovators to support and how much to give each one. The allocation affects an innovator's chance of success, but it also changes the competition that successful innovators face. Gao, Fan, Huang and Chen study this interaction in a two-stage model: a principal allocates an essential resource, then two agents choose costly innovation efforts. Their main result identifies when the principal supports nobody, one agent, or both agents equally. The source is the February 2021 SSRN preprint, especially §3 and Theorem 1 on p. 15. The paper presents a known result; the mission asks for a machine-checked account of its mathematical statement.

The two-stage setting

The principal has resource capacity Bˉ>0\bar B>0Bˉ>0 and selects an allocation (b1,b2)(b_1,b_2)(b1​,b2​) with bi≥0b_i\ge0bi​≥0 and b1+b2≤Bˉb_1+b_2\le\bar Bb1​+b2​≤Bˉ. An agent receiving bib_ibi​ chooses effort xi≥0x_i\ge0xi​≥0 at cost xix_ixi​. The agent succeeds with probability pi=1−e−bixip_i=1-e^{-b_ix_i}pi​=1−e−bi​xi​; the two innovation outcomes are independent. An unfunded agent has zero chance of success at every effort and optimally chooses zero effort. These are the primitives of §3.1, pp. 6–7, and equation (1) of the preprint.

A successful product earns 111 if the other innovation fails. If both innovations succeed, each product earns α∈[0,1]\alpha\in[0,1]α∈[0,1]. The profit-sharing rate γ∈(0,1)\gamma\in(0,1)γ∈(0,1) gives the successful agent the fraction γ\gammaγ of its own product's profit; the principal receives the rest. Agent iii's expected payoff, as a function of both efforts, is γpi(αpj+1−pj)−xi\gamma p_i(\alpha p_j+1-p_j)-x_iγpi​(αpj​+1−pj​)−xi​. The agents choose efforts simultaneously. An effort equilibrium means both efforts are nonnegative and each is a best response among all nonnegative efforts to the other's choice.

The principal's expected profit at an allocation and its equilibrium efforts is

Π(b1,b2;x1,x2)=(1−γ)[2αp1p2+p1(1−p2)+p2(1−p1)].\Pi(b_1,b_2;x_1,x_2)=(1-\gamma)\bigl[2\alpha p_1p_2+p_1(1-p_2)+p_2(1-p_1)\bigr].Π(b1​,b2​;x1​,x2​)=(1−γ)[2αp1​p2​+p1​(1−p2​)+p2​(1−p1​)].

The two-product term counts both successful products, while the other terms count outcomes with exactly one success. Equation (7), p. 11, asks the principal to maximize this profit over feasible resource allocations and the agents' equilibrium behavior. Here BBB denotes the amount invested in a comparison strategy; Bˉ\bar BBˉ remains the available capacity. The paper distinguishes them in §3.3 even where a text extraction loses the overbar.

Formalization targets

The goal is Theorem 1, p. 15. Put t=γBˉt=\gamma\bar Bt=γBˉ and a0=62−8a_0=6\sqrt2-8a0​=62​−8. Where α≥a0\alpha\ge a_0α≥a0​ and α≠1/2\alpha\ne1/2α=1/2, define

L(α)=1−α−α2+16α−81−2α,H(α)=1−α+α2+16α−81−2α.L(\alpha)=\frac{1-\alpha-\sqrt{\alpha^2+16\alpha-8}}{1-2\alpha},\qquad H(\alpha)=\frac{1-\alpha+\sqrt{\alpha^2+16\alpha-8}}{1-2\alpha}.L(α)=1−2α1−α−α2+16α−8​​,H(α)=1−2α1−α+α2+16α−8​​.

The claimed allocation is (0,0)(0,0)(0,0) when t≤1t\le1t≤1; it is (Bˉ,0)(\bar B,0)(Bˉ,0) when 1<t≤21<t\le21<t≤2. For t>2t>2t>2, it is (Bˉ,0)(\bar B,0)(Bˉ,0) when α≤a0\alpha\le a_0α≤a0​. When a0<α<1/2a_0<\alpha<1/2a0​<α<1/2, the theorem selects an equal split (Bˉ/2,Bˉ/2)(\bar B/2,\bar B/2)(Bˉ/2,Bˉ/2) for t∈[L(α),H(α)]t\in[L(\alpha),H(\alpha)]t∈[L(α),H(α)], and the one-agent allocation otherwise. When α≥1/2\alpha\ge1/2α≥1/2, the equal split becomes optimal at and above the lower threshold; below that threshold the one-agent allocation is optimal. At α=1/2\alpha=1/2α=1/2 the threshold is 999, the continuous value of the printed expression.

Selected allocation for t>2, α≥12={(Bˉ/2,Bˉ/2),t≥C(α),(Bˉ,0),t<C(α),C(α)={9,α=12,L(α),α>12.\text{Selected allocation for }t>2,\ \alpha\ge\tfrac12 =\begin{cases} (\bar B/2,\bar B/2),&t\ge C(\alpha),\\ (\bar B,0),&t<C(\alpha), \end{cases} \qquad C(\alpha)=\begin{cases}9,&\alpha=\tfrac12,\\L(\alpha),&\alpha>\tfrac12.\end{cases}Selected allocation for t>2, α≥21​={(Bˉ/2,Bˉ/2),(Bˉ,0),​t≥C(α),t<C(α),​C(α)={9,L(α),​α=21​,α>21​.​

The theorem names an optimal allocation in each region; symmetrically exchanging the agents gives another named form. At a boundary where the two strategies tie, either can be optimal. The six milestones cover the single-agent effort and profit formulas, the equal-split failure rate and profit, the endpoint reduction for a fixed total investment, and the two profit comparisons that locate the competition threshold and the middle band. All indices and formulas come from pp. 9–15 and 39 of the preprint.

What the result gives

The theorem translates the interaction between resource scarcity and product-market competition into an explicit allocation rule. Its middle regime has a bounded interval of resource abundance in which supporting both innovators is best. Past the upper end, supporting one can again be better even though additional resources raise each agent's potential success. This matters whenever an allocation changes both innovation incentives and the rewards available after success; the paper discusses venture investment and grant allocation as examples in §1 and §3.3 of the preprint.

The published paper supplies the mathematical result. A complete Lean development would additionally establish that its equilibrium model, profit comparisons, and boundary cases imply the region theorem under explicit standing assumptions. The goal and milestones here are open statements with compiled Lean syntax; they do not yet have machine-checked proofs. The mission reuses a published generic two-player Nash predicate, while its paper-specific effort-game definitions could support formalizations of related allocation games.

Where the difficulty lies

More resources make success easier at a fixed effort, yet an allocation also changes each agent's effort incentive through the other agent's chance of entering the product market. Consequently, increasing an individual resource share cannot by itself rank the principal's profits across allocations. The equal-split profit can even decrease as total investment grows when α<1/2\alpha<1/2α<1/2; Lemma 3 (i), p. 14, identifies its peak. A comparison of only the one-agent and equal-split formulas would leave every asymmetric split unchecked. The principal's optimization therefore needs a statement that covers all feasible splits and all their effort equilibria. The paper's Proposition 1 addresses the fixed-total allocation question, while its later comparisons determine which endpoint wins.

Formalization scope and conventions

Lean uses real-valued resources and efforts, Real.exp for the success function, and nonnegative real action subtypes for the reused two-player pure Nash predicate. The bounds Bˉ>0\bar B>0Bˉ>0, γ∈(0,1)\gamma\in(0,1)γ∈(0,1) and α∈[0,1]\alpha\in[0,1]α∈[0,1] are explicit. The goal's IsOptimal predicate requires a feasible named allocation, at least one equilibrium there, and profit dominance for every equilibrium of it over every equilibrium of every feasible allocation. This requirement prevents a missing equilibrium from making the claim vacuous. The principal's profit is defined from innovation probabilities, not from the closed-form one-agent and equal-split answers.

Effort is the model's primitive so the allocations (Bˉ,0)(\bar B,0)(Bˉ,0) and (0,0)(0,0)(0,0) retain their intended meaning; a failure-rate substitution would divide by zero there. Closed forms involving Real.log, Real.sqrt or division appear only in the source's parameter regimes where their arguments and denominators are valid. At α=0\alpha=0α=0 an equal split may have many equilibria; the formula milestone asserts existence there and states uniqueness only for α>0\alpha>0α>0. The paper's Proposition 1 says an optimum “must” have endpoint form, but zero-profit cases allow other optima. Its milestone states the endpoint-domination conclusion supplied by its proof. Theorem 1's region-c threshold is corrected to 999 at α=1/2\alpha=1/2α=1/2, where the printed fraction is 0/00/00/0.

The definitions and six milestones provide targets for equilibrium existence, payoff analysis, comparisons across asymmetric allocations, and the exact threshold algebra. Further contributions can develop those proofs and reusable results on best responses of real-action games. The paper's endogenous profit-sharing and other §4 extensions use different optimization problems and are outside this mission.

Selected references

  • Gao, P., X. Fan, Y. Huang and Y.-J. Chen, Resource Allocation Among Competing Innovators, SSRN preprint 3658157, February 2021, pp. 6–15 and 37–39. SSRN abstract and paper.
9 thms2 active usersReviewed
Quantum Information·Captain: Goku

Dividing Quantum ChannelsResearch Paper

Motivation

We investigate the possibility of dividing quantum channels into concatenations of other channels, thereby studying the semigroup structure of the set of completely-positive trace-preserving maps. We show the existence of 'indivisible' channels which can not be written as non-trivial products of other channels and study the set of 'infinitesimal divisible' channels which are elements of continuous completely positive evolutions. For qubit channels we obtain a complete characterization of the sets of indivisible and infinitesimal divisible channels. Moreover, we identify those channels which are solutions of time-dependent master equations for both positive and completely positive evolutions. For arbitrary finite dimension we prove a representation theorem for elements of continuous completely positive evolutions based on new results on determinants of quantum channels and Markovian approximations.

This mission is the statement-level formalization of Dividing Quantum Channels (arXiv:math-ph/0611057v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

23 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Theorem 16 (Structure of infinitesimal divisible channels) (Theorem 16 (Structure of infinitesimal divisible channels), PDF p. 14). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

1 results of the paper are not stated yet, because the library lacks an interface they need:

  • Theorem 19; PDF p.18 Eq.(40) and class-2 paragraph: A source-correct finite-time versus singular-boundary domain for Theorem 19 (source-ambiguity)

Selected references

  • Dividing Quantum Channels, arXiv:math-ph/0611057v3, https://arxiv.org/abs/math-ph/0611057v3
32 thms2 active usersReviewed
Quantum Information·Captain: Goku

Converse bounds for private communication over quantum channelsResearch Paper

Motivation

This paper establishes several converse bounds on the private transmission capabilities of a quantum channel. The main conceptual development builds firmly on the notion of a private state, which is a powerful, uniquely quantum method for simplifying the tripartite picture of privacy involving local operations and public classical communication to a bipartite picture of quantum privacy involving local operations and classical communication. This approach has previously led to some of the strongest upper bounds on secret key rates, including the squashed entanglement and the relative entropy of entanglement. Here we use this approach along with a "privacy test" to establish a general meta-converse bound for private communication, which has a number of applications. The meta-converse allows for proving that any quantum channel's relative entropy of entanglement is a strong converse rate for private communication. For covariant channels, the meta-converse also leads to second-order expansions of relative entropy of entanglement bounds for private communication rates. For such channels, the bounds also apply to the private communication setting in which the sender and receiver are assisted by unlimited public classical communication, and as such, they are relevant for establishing various converse bounds for quantum key distribution protocols conducted over these channels. We find precise characterizations for several channels of interest and apply the methods to establish several converse bounds on the private transmission capabilities of all phase-insensitive bosonic channels.

This mission is the statement-level formalization of Converse bounds for private communication over quantum channels (arXiv:1602.08898v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

7 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Covariant channels admit a fixed Choi-state teleportation simulation (Proposition 2, PDF p. 7). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

25 results of the paper are not stated yet, because the library lacks an interface they need:

  • Theorem 11: CPPP protocol outputs and one-use private rate supremum (hard)
  • (3.14)–(3.15): Three operational rate and error boundaries with extended endpoint conventions (hard)
  • (3.16): Actual adaptive LOCC private-protocol output and fixed-resource simulation (hard)
  • (3.18): Entanglement and private transmission feasible regions in three assistance classes (hard)
  • (4.33): Parallel CPPP private boundary and channel testing REE (hard)
  • (4.34): Adaptive private boundary for a fixed simulation resource (hard)
  • Theorem 12: Two-way private protocol sequences and strong-converse threshold (hard)
  • Theorem 13: CPPP private protocol sequences and strong-converse threshold (hard)
  • (5.36)–(5.37): Optimal adaptive private fidelity and tensor-resource sandwiched REE (hard)
  • (5.44)–(5.46): Optimal CPPP private fidelity and polynomial prefactor (hard)
  • Remark 16: Regularized operational strong-converse thresholds (hard)
  • Proposition 17: Generalized-dephasing operational capacities and coherent-information maximum (hard)
  • Proposition 18: Flagged erasure channel and assisted capacities (hard)
  • Theorem 19: Operational second-order private boundaries and variance optimization over REE minimizers (hard)
  • (6.11): Unassisted quantum/private boundaries and coherent-information dispersion (hard)
  • Proposition 21: An exact positive integer output rank compatible with (6.15) (source-ambiguity)
  • (6.16): CPPP quantum/private boundaries and reverse coherent-information dispersion (hard)
  • Proposition 22: Singular zero-variance dephasing case and meaning of shared expansions (source-ambiguity)
  • Proposition 23: Definition and rounding convention for k in exact erasure equation (7.5) (source-ambiguity)
  • (7.6): Qubit erasure assisted operational boundaries (hard)
  • (7.7): Normal-state adaptive protocols and separable full output (hard)
  • Theorem 24: Physical Gaussian channels on full oscillator spaces and actual adaptive private protocols (hard)
  • Corollary 25: Unconstrained and constrained bosonic operational capacities and strong-converse thresholds (hard)
  • (D.12)–(D.14): Consistent physical Gaussian comparison states for the variance expansions (source-ambiguity)
  • Proposition 31: Injective trace-class states, tensor products, and relative modular spectral variance (hard)

Selected references

  • Converse bounds for private communication over quantum channels, arXiv:1602.08898v3, https://arxiv.org/abs/1602.08898v3
19 thms2 active usersReviewed
Quantum Information·Captain: Goku

On Feedback and the Classical Capacity of a Noisy Quantum ChannelResearch Paper

Motivation

In Shannon information theory the capacity of a memoryless communication channel cannot be increased by the use of feedback from receiver to sender. In this paper the use of classical feedback is shown to provide no increase in the unassisted classical capacity of a memoryless quantum channel when feedback is used across non-entangled input states, or when the channel is an entanglement--breaking channel. This gives a generalization of the Shannon theory for certain classes of feedback protocols when transmitting through noisy quantum communication channels.

This mission is the statement-level formalization of On Feedback and the Classical Capacity of a Noisy Quantum Channel (arXiv:quant-ph/0305176v1). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

6 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is No capacity gain across separable feedback cuts (III.B, PDF p. 4). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

1 results of the paper are not stated yet, because the library lacks an interface they need:

  • III.A, (7), (20), and the following induction sentence: An executed multi-block product-alphabet interface that distinguishes future forward-input registers from retained local auxiliary purifiers, and enforces the product restriction on the actually prepared inputs after each feedback history. (hard)

Selected references

  • On Feedback and the Classical Capacity of a Noisy Quantum Channel, arXiv:quant-ph/0305176v1, https://arxiv.org/abs/quant-ph/0305176v1
11 thms2 active usersReviewed
Quantum Information·Captain: Goku

The Information-Disturbance Tradeoff and the Continuity of Stinespring's RepresentationResearch Paper

Motivation

Stinespring's dilation theorem is the basic structure theorem for quantum channels: it states that any quantum channel arises from a unitary evolution on a larger system. Here we prove a continuity theorem for Stinespring's dilation: if two quantum channels are close in cb-norm, then it is always possible to find unitary implementations which are close in operator norm, with dimension-independent bounds. This result generalizes Uhlmann's theorem from states to channels and allows to derive a formulation of the information-disturbance tradeoff in terms of quantum channels, as well as a continuity estimate for the no-broadcasting theorem. We briefly discuss further implications for quantum cryptography, thermalization processes, and the black hole information loss puzzle.

This mission is the statement-level formalization of The Information-Disturbance Tradeoff and the Continuity of Stinespring's Representation (arXiv:quant-ph/0605009v1). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

8 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Continuity with freely chosen common Stinespring dilations (§I, Eq. (1), PDF p. 1). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

3 results of the paper are not stated yet, because the library lacks an interface they need:

  • Theorem 1, Eq. (18): A valid prescribed-environment left continuity inequality, and a source for the requested modified KSW interface. (source-ambiguity)
  • §V, claimed absence of recovery after Eq. (55): A precise no-recovery claim with hypotheses stronger than small environment alone. (source-ambiguity)
  • §VII, generic-energy-constraint extension: Specified energy operators, energy bounds, admissible inputs and channels, and the constrained norm domain. (source-ambiguity)

Selected references

  • The Information-Disturbance Tradeoff and the Continuity of Stinespring's Representation, arXiv:quant-ph/0605009v1, https://arxiv.org/abs/quant-ph/0605009v1
19 thms2 active usersReviewed
Quantum Information·Captain: Goku

Bounding the forward classical capacity of bipartite quantum channelsResearch Paper

Motivation

We introduce various measures of forward classical communication for bipartite quantum channels. Since a point-to-point channel is a special case of a bipartite channel, the measures reduce to measures of classical communication for point-to-point channels. As it turns out, these reduced measures have been reported in prior work of Wang et al. on bounding the classical capacity of a quantum channel. As applications, we show that the measures are upper bounds on the forward classical capacity of a bipartite channel. The reduced measures are upper bounds on the classical capacity of a point-to-point quantum channel assisted by a classical feedback channel. Some of the various measures can be computed by semi-definite programming.

This mission is the statement-level formalization of Bounding the forward classical capacity of bipartite quantum channels (arXiv:2010.01058v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

42 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Theorem 21 (main paper result selected by page-1 seed) (Theorem 21 (main paper result selected by page-1 seed), PDF p. 14). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

6 results of the paper are not stated yet, because the library lacks an interface they need:

  • Proposition 11 (Non-negativity): Scalar-zero nonnegativity in the literal generalized-divergence axioms (142)-(144). (source-ambiguity)
  • Proposition 13 (Zero on classical feedback channels): Scalar-zero nonnegativity in the literal generalized-divergence axioms (142)-(144). (source-ambiguity)
  • Proposition 14 (Zero on tensor product of local channels): Scalar-zero nonnegativity in the literal generalized-divergence axioms (142)-(144). (source-ambiguity)
  • Proposition 24 (Subadditivity): A source-specified amortized divergence domain for arbitrary CP numerators, including zero outputs, and extended subtraction conventions. (source-ambiguity)
  • Remark 38: An explicit geometric Renyi lower-semicontinuity extension range beyond the operator-convex/DPI range. (source-ambiguity)
  • Unnumbered regularized sandwiched composition bound (299): A source-specified amortized divergence domain for arbitrary CP numerators, including zero outputs, and extended subtraction conventions. (source-ambiguity)

Selected references

  • Bounding the forward classical capacity of bipartite quantum channels, arXiv:2010.01058v3, https://arxiv.org/abs/2010.01058v3
54 thms2 active usersReviewed
Control TheoryPartial Differential EquationsProbability·Captain: mikedeng1

Nonconcave Utility Maximization with Portfolio Bounds: The Value Function Is the Unique Viscosity Solution of the HJB Equation under the New Terminal Asymptotic ConditionResearch Paper

Motivation

An investor may care about reaching a target, avoiding a loss, or crossing an aspiration level rather than maximizing a concave function of final wealth. A target reward can jump from zero to one at a specified wealth. Such nonconcave utility is a natural model for goal-reaching portfolios, but its discontinuity changes what the associated Hamilton–Jacobi–Bellman equation can say at maturity. Portfolio bounds make the distinction sharper: an investor with finite leverage and short-sale limits cannot instantaneously smooth a jump in the payoff. Dai, Kou, Qian and Wan analyze this combination of nonconcavity, portfolio constraints, and a liquidation floor in their 2022 paper.

The paper proves a comparison principle and identifies the control value as the unique viscosity solution under a special terminal asymptotic condition. These are known mathematical results; this mission asks for their Lean proofs. The source is the authors' accepted manuscript, whose main theorem is Theorem 4.2 on printed page 12. The e-companion supplies boundary and terminal results supporting that theorem.

Setting

The market contains one risky stock and one riskless bond. After the paper's forward-wealth normalization, wealth WsW_sWs​ started from Wt=wW_t=wWt​=w follows

dWs=Wsπs(η ds+σ dBs),t≤s≤T.dW_s=W_s\pi_s(\eta\,ds+\sigma\,d\mathcal B_s),\qquad t\le s\le T.dWs​=Ws​πs​(ηds+σdBs​),t≤s≤T.

Here η\etaη is the excess stock return, σ>0\sigma>0σ>0 is volatility, B\mathcal BB is Brownian motion, and πs\pi_sπs​ is the fraction of wealth invested in the stock. Portfolio weights satisfy d≤πs≤ud\le\pi_s\le ud≤πs​≤u, with d≤0≤ud\le0\le ud≤0≤u; either endpoint may be infinite. Wealth remains above the liquidation floor B≥0B\ge0B≥0. For utility UUU, the value function is

V(t,w)=sup⁡π admissibleE[U(WT)∣Wt=w].V(t,w)=\sup_{\pi\text{ admissible}}\mathbb E[U(W_T)\mid W_t=w].V(t,w)=π admissiblesup​E[U(WT​)∣Wt​=w].

Assumption 3.1 permits utility to be nondecreasing and right-continuous without being concave or continuous. For some 0<p^<10<\hat p<10<p^​<1, it eventually satisfies U(w)≤wp^U(w)\le w^{\hat p}U(w)≤wp^​. At w=Bw=Bw=B it either has a finite value or, when B=0B=0B=0, has the paper's CRRA form near zero. The second case includes logarithmic utility. These alternatives lead to different liquidation boundary conditions.

The formalized Hamiltonian is

H(w,p,A)=sup⁡d≤π≤u{12π2w2σ2A+πwηp},H(w,p,A)=\sup_{d\le\pi\le u}\left\{\frac12\pi^2w^2\sigma^2A+\pi w\eta p\right\},H(w,p,A)=d≤π≤usup​{21​π2w2σ2A+πwηp},

and the HJB equation is −Vt−H(w,Vw,Vww)=0-V_t-H(w,V_w,V_{ww})=0−Vt​−H(w,Vw​,Vww​)=0 for t<Tt<Tt<T and w>Bw>Bw>B. Definition A.1 tests upper and lower semicontinuous envelopes of candidate solutions against smooth functions and uses the corresponding envelopes H∗H^*H∗ and H∗H_*H∗​. It also imposes the liquidation boundary condition and a terminal asymptotic condition. For bounded portfolio weights the terminal condition retains the jump of UUU through the normal distribution function Φ\PhiΦ and L=σmax⁡{u,−d}L=\sigma\max\{u,-d\}L=σmax{u,−d}. For unbounded weights its target is the concave envelope U^\hat UU^.

Formalization targets

Value-function characterization

The goal is Theorem 4.2: for both bounded and unbounded portfolio intervals, the control value satisfies Definition A.1 and is continuous on [0,T)×(B,∞)[0,T)\times(B,\infty)[0,T)×(B,∞). In the growth class used by Theorem 4.1, every other viscosity solution agrees with it:

V′(t,w)=V(t,w),0<t<T,w>B.V'(t,w)=V(t,w),\qquad 0<t<T,\quad w>B.V′(t,w)=V(t,w),0<t<T,w>B.

The goal keeps the actual stochastic-control supremum as VVV and quantifies over competing solutions V′V'V′. It does not select a particular numerical method or a preferred proof. Theorem 4.1 gives comparison in this class. Proposition EC.3.2 gives the liquidation boundary behavior. Proposition EC.3.3 gives two terminal regimes, and Lemma EC.3.3 supplies the power-majorant statement used in the unbounded regime. The milestone list follows these stated results, specialized to the one-stock constant-coefficient model of the main theorem.

Significance

The characterization connects a portfolio optimization problem to an HJB equation even when the terminal utility jumps. It specifies the terminal behavior that distinguishes the bounded and unbounded portfolio regimes. In the bounded case a discontinuity can persist in the approach to maturity; in the unbounded case the limiting target is the concave envelope. The comparison statement then makes the characterization unique within the stated growth class. These conclusions are the analytical basis for the paper's later discussion of numerical schemes, although the numerical convergence theorem is outside this mission's scope (Dai et al., 2022, §§4 and EC.3).

A complete formalization would produce reusable definitions of the constrained control value, the extended-real Hamiltonian and its envelopes, and terminal limits for discontinuous payoffs. The paper's results are proved on paper but have no machine-checked proof in this proposal. The declarations here are compiled statements awaiting proofs. Independent work on the comparison theorem, boundary behavior, terminal asymptotics, and supporting real analysis can proceed against the same definition layer.

Difficulty

The usual terminal condition V(T,w)=U(w)V(T,w)=U(w)V(T,w)=U(w) does not describe the limit of V(t,ζ)V(t,\zeta)V(t,ζ) as (t,ζ)(t,\zeta)(t,ζ) approaches (T,w)(T,w)(T,w) when UUU jumps. Replacing the limit by U(w)U(w)U(w) would erase the singular behavior that the paper studies. The bounded-portfolio condition instead depends on the left limit U(w−)U(w-)U(w−), the size of the jump, and the scaled quantity log⁡(ζ/w)/T−t\log(\zeta/w)/\sqrt{T-t}log(ζ/w)/T−t​. A viscosity comparison argument must handle this terminal profile while the Hamiltonian itself can be infinite or discontinuous in the unbounded portfolio regime. The liquidation boundary has a separate CRRA asymptotic when utility diverges at zero. Each of these clauses is part of the solution concept and must remain compatible with the value function.

Formalization scope

The Lean market stores η,σ,T,B\eta,\sigma,T,Bη,σ,T,B as real numbers and d,ud,ud,u as extended real endpoints. It assumes σ>0\sigma>0σ>0, T>0T>0T>0, B≥0B\ge0B≥0, d≤0≤ud\le0\le ud≤0≤u, and at least one nonzero admissible weight. The last three inequalities include the paper's standing bounds and exclude L=0L=0L=0. Admissible controls are progressively measurable, obey the bounds and liquidation floor, satisfy the integral wealth equation through a Brownian Itô integral, and have integrable terminal utility. The supremum of their expectations is extended real so an infinite value is preserved; the goal explicitly proves finiteness before converting it to a real value. Brownian motions are quantified over filtered probability spaces and have independent future increments relative to their filtration.

The PDE domain is D=[0,T)×(B,∞)D=[0,T)\times(B,\infty)D=[0,T)×(B,∞). Semicontinuous envelopes and boundary and terminal limits approach within DDD. Smooth tests are C∞C^\inftyC∞ real functions. The Hamiltonian and its envelopes are extended real; finite-width expressions involving LLL are used only under bounded portfolio endpoints. The terminal point w=Bw=Bw=B is included only for the finite-utility boundary branch, where the source defines U(B−)=U(B)U(B-)=U(B)U(B−)=U(B). The CRRA formula uses a logarithmic branch at zero power, avoiding division by zero. These commitments rule out a vacuous solution notion or a value function defined as an arbitrary viscosity solution. Proving the control value finite, nontrivial comparison, and both terminal limits remains part of the mission. The e-companion's multivariate statements are included only in the one-stock constant-coefficient specialization used by Theorems 4.1–4.2.

Selected references

  • M. Dai, S. Kou, S. Qian and X. Wan, Nonconcave utility maximization with portfolio bounds, Management Science 68(11), 8368–8385, 2022. DOI: 10.1287/mnsc.2021.4228. This mission cites the authors' accepted manuscript, including its e-companion.
9 thms2 active usersReviewed
Quantum Information·Captain: Goku

Quantum hypothesis testing and the operational interpretation of the quantum Renyi relative entropiesResearch Paper

Motivation

We show that the new quantum extension of Renyi's \alpha-relative entropies, introduced recently by Muller-Lennert, Dupuis, Szehr, Fehr and Tomamichel, J. Math. Phys. 54, 122203, (2013), and Wilde, Winter, Yang, Commun. Math. Phys. 331, (2014), have an operational interpretation in the strong converse problem of quantum hypothesis testing. Together with related results for the direct part of quantum hypothesis testing, known as the quantum Hoeffding bound, our result suggests that the operationally relevant definition of the quantum Renyi relative entropies depends on the parameter \alpha: for \alpha<1, the right choice seems to be the traditional definition, whereas for \alpha>1 the right choice is the newly introduced version. As a sideresult, we show that the new Renyi \alpha-relative entropies are asymptotically attainable by measurements for \alpha>1, and give a new simple proof for their monotonicity under completely positive trace-preserving maps.

This mission is the statement-level formalization of Quantum hypothesis testing and the operational interpretation of the quantum Renyi relative entropies (arXiv:1309.3228v5). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

35 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Exact strong converse exponent in quantum hypothesis testing (Theorem IV.10, PDF p. 15). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

4 results of the paper are not stated yet, because the library lacks an interface they need:

  • Corollary IV.6: interior a_alpha construction (source-ambiguity)
  • Lemma IV.16, (92)-(93): restricted interior infimum in (93) (source-ambiguity)
  • Proposition A.3: quantum new divergence at order zero (source-ambiguity)
  • Appendix (A3): tensor scaling assumption in generic attainment implications (source-ambiguity)

Selected references

  • Quantum hypothesis testing and the operational interpretation of the quantum Renyi relative entropies, arXiv:1309.3228v5, https://arxiv.org/abs/1309.3228v5
42 thms2 active usersReviewed
Quantum Information·Captain: Goku

Elements in pointed invariant cones in Lie algebras and corresponding affine pairsResearch Paper

Motivation

In this note we study in a finite dimensional Lie algebra g{\mathfrak g}g the set of all those elements x for which the closed convex hull of the adjoint orbit contains no affine lines; this contains in particular elements whose adjoint orbits generates a pointed convex cone~CxC_xCx​. Assuming that g{\mathfrak g}g is admissible, i.e., contains a generating invariant convex subset not containing affine lines, we obtain a natural characterization of such elements, also for non-reductive Lie algebras. Motivated by the concept of standard (Borchers) pairs in QFT, we also study pairs (x,h)(x,h)(x,h) of Lie algebra elements satisfying [h,x]=x[h,x]=x[h,x]=x for which CxC_xCx​ pointed. Given xxx, we show that such elements hhh can be constructed in such a way that adh{\rm ad} hadh defines a 555-grading, and characterize the cases where we even get a 333-grading.

This mission is the statement-level formalization of Elements in pointed invariant cones in Lie algebras and corresponding affine pairs (arXiv:2110.07297v1). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

33 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Theorem 3.20: Characterization Theorem (Theorem 3.20: Characterization Theorem, PDF p. 14). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

14 results of the paper are not stated yet, because the library lacks an interface they need:

  • Lemma 3.5: Claimed gl2 subalgebra in a pointed cone: A consistent printed theorem with unambiguous boundary hypotheses (source-ambiguity)
  • Proposition 3.15: Claimed extension to a generating invariant cone: A consistent printed theorem with unambiguous boundary hypotheses (source-ambiguity)
  • Lemma 3.17: Root formula for the central quadratic cone: Complexified root spaces, the star real-form involution, solvable roots, adapted positive systems, and their central root cones and real Cartan sections (hard)
  • Proposition 3.18: Generating l-cone and its Cartan section: Complexified root spaces, the star real-form involution, solvable roots, adapted positive systems, and their central root cones and real Cartan sections (hard)
  • Remark 3.19: Construction of a pointed invariant cone from central data: Complexified root spaces, the star real-form involution, solvable roots, adapted positive systems, and their central root cones and real Cartan sections (hard)
  • Corollary 3.23: Jacobi algebra: semibounded Hamiltonians characterize pointedness: Concrete Jacobi/Poisson Lie algebra hsp_(2n)(R), its actual symplectic matrix action, compatible bracket and normalized Hamiltonian identification (hard)
  • Example 3.24: Two-dimensional nonnegative quadratic Hamiltonians: Concrete Jacobi/Poisson Lie algebra hsp_(2n)(R), its actual symplectic matrix action, compatible bracket and normalized Hamiltonian identification (hard)
  • Example 3.25: Counterexample to extension of pointed cones: Concrete real Lie algebra with l=R^2, V=C^4, z=R^2 and the specified conjugate-bilinear beta (hard)
  • Proposition 3.26: Extension in the Jacobi algebra: Concrete Jacobi/Poisson Lie algebra hsp_(2n)(R), its actual symplectic matrix action, compatible bracket and normalized Hamiltonian identification (hard)
  • Example 4.3: A generating invariant cone need not be canonically dilation invariant: Concrete Jacobi/Poisson Lie algebra hsp_(2n)(R), its actual symplectic matrix action, compatible bracket and normalized Hamiltonian identification (hard)
  • Remark 4.4: Outer-derivation invariance of constructed cones: Complexified root spaces, the star real-form involution, solvable roots, adapted positive systems, and their central root cones and real Cartan sections (hard)
  • Example 4.13: Oscillator Euler-element obstruction as printed: A consistent printed theorem with unambiguous boundary hypotheses (source-ambiguity)
  • Lemma 4.15: Criterion for a nonzero Euler derivation extending ad_l h: A consistent printed theorem with unambiguous boundary hypotheses (source-ambiguity)
  • Example 4.18: Six-dimensional module example for Euler derivations: A consistent printed theorem with unambiguous boundary hypotheses (source-ambiguity)

Selected references

  • Elements in pointed invariant cones in Lie algebras and corresponding affine pairs, arXiv:2110.07297v1, https://arxiv.org/abs/2110.07297v1
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Locking entanglement measures with a single qubitResearch Paper

Motivation

We study the loss of entanglement of bipartite state subjected to discarding or measurement of one qubit. Examining the behavior of different entanglement measures, we find that entanglement of formation, entanglement cost, and logarithmic negativity are lockable measures in that it can decrease arbitrarily after measuring one qubit. We prove that any convex and asymptotically non-continuous measure is lockable. As a consequence, all the convex roof measures can be locked. Relative entropy of entanglement is shown to be a non-lockable measure.

This mission is the statement-level formalization of Locking entanglement measures with a single qubit (arXiv:quant-ph/0404096v1). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

7 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is One-qubit locking of formation, operational cost, and logarithmic negativity (Eqs. (1)–(3), continuation on p.2, PDF p. 1). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

1 results of the paper are not stated yet, because the library lacks an interface they need:

  • Eqs. (4)–(6): A source-pinned corrected positive density family replacing Eqs. (4)–(5), with a consistent log-negativity formula and parameter domain. (source-ambiguity)

Selected references

  • Locking entanglement measures with a single qubit, arXiv:quant-ph/0404096v1, https://arxiv.org/abs/quant-ph/0404096v1
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Unifying classical and quantum key distillationResearch Paper

Motivation

Assume that two distant parties, Alice and Bob, as well as an adversary, Eve, have access to (quantum) systems prepared jointly according to a tripartite state. In addition, Alice and Bob can use local operations and authenticated public classical communication. Their goal is to establish a key which is unknown to Eve. We initiate the study of this scenario as a unification of two standard scenarios: (i) key distillation (agreement) from classical correlations and (ii) key distillation from pure tripartite quantum states. Firstly, we obtain generalisations of fundamental results related to scenarios (i) and (ii), including upper bounds on the key rate. Moreover, based on an embedding of classical distributions into quantum states, we are able to find new connections between protocols and quantities in the standard scenarios (i) and (ii). Secondly, we study specific properties of key distillation protocols. In particular, we show that every protocol that makes use of pre-shared key can be transformed into an equally efficient protocol which needs no pre-shared key. This result is of practical significance as it applies to quantum key distribution (QKD) protocols, but it also implies that the key rate cannot be locked with information on Eve's side. Finally, we exhibit an arbitrarily large separation between the key rate in the standard setting where Eve is equipped with quantum memory and the key rate in a setting where Eve is only given classical memory. This shows that assumptions on the nature of Eve's memory are important in order to determine the correct security threshold in QKD.

This mission is the statement-level formalization of Unifying classical and quantum key distillation (arXiv:quant-ph/0608199v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

4 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Pure-state intrinsic information equals twice marginal squashed entanglement (pure-intrinsic-squashed, PDF p. 8). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

21 results of the paper are not stated yet, because the library lacks an interface they need:

  • classical-versus-quantum-memory: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Quantum-versus-classical Eve-memory operational rates for Eq.(51) (hard)
  • theorem-3.1: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Secrecy monotones on dimension-varying LOPC states and their extended regularization (hard)
  • corollary-3.2: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational purification/private-state protocol bridge (hard)
  • corollary-3.3: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Distillable key under arbitrary purifying-register allocation (hard)
  • theorem-3.5: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD in the intrinsic-information bound (hard)
  • theorem-3.7: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD with physical enlarged squashed-entanglement cut (hard)
  • theorem-3.9: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD and marginal-constrained reduced intrinsic information (hard)
  • theorem-3.11: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD in the regularized relative-entropy bound (hard)
  • bell-comparison: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD and reduced intrinsic quantities in Eqs.(16)–(17) (hard)
  • locking-comparison-example: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD of the explicit normalized Eq.(24) witness (hard)
  • unbounded-intrinsic-comparison: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD in the existential unbounded-gap comparison (hard)
  • theorem-3.12: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD and LOPC-accessible information of every supplied product ensemble (hard)
  • theorem-3.14: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational distillable common randomness with communication charged once (hard)
  • coherent-protocol-commutation: Consistent source statement for the prescribed coherent protocol and unrestricted KD (source-ambiguity)
  • theorem-4.1: Consistent source statement for the prescribed coherent protocol and unrestricted KD (source-ambiguity)
  • corollary-4.2: Consistent source statement for the prescribed coherent protocol and unrestricted KD (source-ambiguity)
  • theorem-5.1: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Protocol-level replacement on the genuinely extended Eve input (hard)
  • corollary-5.2: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Supremal key-rate comparison under Eve-system loss (hard)
  • corollary-5.3: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Protocol replacement consuming ell secret bits per input copy (hard)
  • quantum-locking-factor-sharp: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Operational KD of the normalized four-Bell-label example (hard)
  • lemma-A.1: Evaluated finite tripartite LOPC protocols and their operational distillable-key rate (Definitions 2.1–2.2); Communication-counted, rate-approximating protocol replacements (hard)

Selected references

  • Unifying classical and quantum key distillation, arXiv:quant-ph/0608199v3, https://arxiv.org/abs/quant-ph/0608199v3
11 thms2 active usersReviewed
Quantum Information·Captain: Goku

Contractivity of positive and trace preserving maps under Lₚ normsResearch Paper

Motivation

We provide a complete picture of contractivity of trace preserving positive maps with respect to ppp-norms. We show that for p>1p>1p>1 contractivity holds in general if and only if the map is unital. When the domain is restricted to the traceless subspace of Hermitian matrices, then contractivity is shown to hold in the case of qubits for arbitrary p≥1p\geq 1p≥1 and in the case of qutrits if and only if p=1,∞p=1,\inftyp=1,∞. In all non-contractive cases best possible bounds on the ppp-norms are derived.

This mission is the statement-level formalization of Contractivity of positive and trace preserving maps under Lₚ norms (arXiv:math-ph/0601063v1). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

10 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Sharp general Schatten-norm bound and trace-map attainment (Theorem II.1 and following attainment clause, PDF p. 2). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

2 results of the paper are not stated yet, because the library lacks an interface they need:

  • §III.A, erroneous unnumbered equality in the qubit introduction: A correct source-supported universal qubit restricted-norm equality (source-ambiguity)
  • §III.B, erroneous qutrit counterexample for non-Hermitian traceless matrices: A correct source-supported non-Hermitian traceless qutrit strict-expansion assertion and witness (source-ambiguity)

Selected references

  • Contractivity of positive and trace preserving maps under Lₚ norms, arXiv:math-ph/0601063v1, https://arxiv.org/abs/math-ph/0601063v1
17 thms2 active usersReviewed
Quantum Information·Captain: Goku

Entanglement Cost of Quantum ChannelsResearch Paper

Motivation

The entanglement cost of a quantum channel is the minimal rate at which entanglement (between sender and receiver) is needed in order to simulate many copies of a quantum channel in the presence of free classical communication. In this paper we show how to express this quantity as a regularised optimisation of the entanglement formation over states that can be generated between sender and receiver. Our formula is the channel analog of a well-known formula for the entanglement cost of quantum states in terms of the entanglement of formation; and shares a similar relation to the recently shattered hope for additivity. The entanglement cost of a quantum channel can be seen as the analog of the quantum reverse Shannon theorem in the case where free classical communication is allowed. The techniques used in the proof of our result are then also inspired by a recent proof of the quantum reverse Shannon theorem and feature the one-shot formalism for quantum information theory, the post-selection technique for quantum channels as well as Sion's minimax theorem. We discuss two applications of our result. First, we are able to link the security in the noisy-storage model to a problem of sending quantum rather than classical information through the adversary's storage device. This not only improves the range of parameters where security can be shown, but also allows us to prove security for storage devices for which no results were known before. Second, our result has consequences for the study of the strong converse quantum capacity. Here, we show that any coding scheme that sends quantum information through a quantum channel at a rate larger than the entanglement cost of the channel has an exponentially small fidelity.

This mission is the statement-level formalization of Entanglement Cost of Quantum Channels (arXiv:1108.5357v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

15 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Operational channel entanglement cost equals regularized maximum formation (Theorem 12 (Eq.22; paper-result seed), PDF p. 7). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

11 results of the paper are not stated yet, because the library lacks an interface they need:

  • Unnumbered result, §III.4: one-way classical communication: A consistent communication-resource model, or a corrected forward-only statement; backward-only simulation cannot transmit the unknown input. (source-ambiguity)
  • Lemma 19: An explicit class of two-party ideal functionalities, correctness and security/composability semantics, a noisy-memory adversary interface, and a simulation reduction with positive rate slack and integer storage rounding. (hard)
  • Unnumbered result, Eq.(78): qubit noisy-storage criterion: The same cryptographic functionality and adversary semantics as Lemma 19, followed by the stated qubit specialization. (hard)
  • Lemma 21: A corrected finite-block theorem in the actual message dimension M_n, or an explicit eventual/liminf rate convention replacing the printed limsup-only hypothesis. (source-ambiguity)
  • Corollary 22: A finite-block message-dimension converse for arbitrary finite-round classical-assisted codes, with a consistent rate convention. (source-ambiguity)
  • Lemma 23: A regularized whole-channel simulation theorem with an explicitly chosen blocking length and the resulting dimension-dependent error exponent and polynomial prefactor, plus corrected slack arithmetic. (source-ambiguity)
  • Theorem 24: A corrected eventual-rate coding statement, controlled simulation constants after blocking, and a specified channel/entanglement fidelity bound distinct from diamond-error lower bounds. (source-ambiguity)
  • Unnumbered result, §IV.2: erasure strong converse: A consistent fixed/eventual-rate strong-converse formulation with specified fidelity and an independent valid proof for the erasure channel. (source-ambiguity)
  • Unnumbered result, Eq.(97): dephasing capacity comparison: A correction of the entanglement-assisted term in (97), together with consistent operational capacity semantics; the printed equality fails at p=1. (source-ambiguity)
  • Unnumbered result, Eq.(98): two-way qubit capacity bound: A complete assisted-code chronology and a theorem relating arbitrary adaptive uses to parallel whole-block simulation, or an explicitly corrected capacity claim. (source-ambiguity)
  • Lemma 42: An explicit all-epsilon entropy extension/saturation rule and corresponding proved bound, or an independently approved small-error-domain correction. (source-ambiguity)

Selected references

  • Entanglement Cost of Quantum Channels, arXiv:1108.5357v3, https://arxiv.org/abs/1108.5357v3
27 thms2 active usersReviewed
Quantum Information·Captain: Goku

Semidefinite programming strong converse bounds for classical capacityResearch Paper

Motivation

We investigate the classical communication over quantum channels when assisted by no-signaling (NS) and positive-partial-transpose-preserving (PPT) codes, for which both the optimal success probability of a given transmission rate and the one-shot ϵ\epsilonϵ-error capacity are formalized as semidefinite programs (SDPs). Based on this, we obtain improved SDP finite blocklength converse bounds of general quantum channels for entanglement-assisted codes and unassisted codes. Furthermore, we derive two SDP strong converse bounds for the classical capacity of general quantum channels: for any code with a rate exceeding either of the two bounds of the channel, the success probability vanishes exponentially fast as the number of channel uses increases. In particular, applying our efficiently computable bounds, we derive an improved upper bound on the classical capacity of the amplitude damping channel. We also establish the strong converse property for the classical and private capacities of a new class of quantum channels. We finally study the zero-error setting and provide efficiently computable upper bounds on the one-shot zero-error capacity of a general quantum channel.

This mission is the statement-level formalization of Semidefinite programming strong converse bounds for classical capacity (arXiv:1610.06381v4). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

26 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Theorem 11: β strong converse bound (original seed pinned from abstract) (Theorem 11, PDF p. 16). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

1 results of the paper are not stated yet, because the library lacks an interface they need:

  • Remark/Fig.6 following Theorem 14: Exact numerical comparator selected from reference [45], and the parameter range and strictness of its comparison with log2(1+sqrt(1-gamma)). (source-ambiguity)

Selected references

  • Semidefinite programming strong converse bounds for classical capacity, arXiv:1610.06381v4, https://arxiv.org/abs/1610.06381v4
38 thms2 active usersReviewed
Quantum Information·Captain: Goku

Non-asymptotic entanglement distillationResearch Paper

Motivation

Entanglement distillation, an essential quantum information processing task, refers to the conversion from multiple copies of noisy entangled states to a smaller number of highly entangled states. In this work, we study the non-asymptotic fundamental limits for entanglement distillation. We investigate the optimal tradeoff between the distillation rate, the number of prepared states, and the error tolerance. First, we derive the one-shot distillable entanglement under completely positive partial transpose preserving operations as a semidefinite program and demonstrate an exact characterization via the quantum hypothesis testing relative entropy. Second, we establish efficiently computable second-order estimations of the distillation rate for general quantum states. In particular, we provide explicit as well as approximate evaluations for various quantum states of practical interest, including pure states, mixture of Bell states, maximally correlated states and isotropic states.

This mission is the statement-level formalization of Non-asymptotic entanglement distillation (arXiv:1706.06221v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

13 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Exact Hermitian hypothesis-testing characterization (Seed abstract main result pinned to Theorem 4, Eq. (25): exact hypothesis-testing characterization, PDF p. 6). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

2 results of the paper are not stated yet, because the library lacks an interface they need:

  • Lemma 6, Eqs.(35)–(37): A consistent printed smooth max-entropy convention and finite-variance support domain for the cited pair of second-order expansions. (source-ambiguity)
  • Appendix B, Algorithm 1, Eqs.(69),(75),(76): A specified admissible reference point/selection rule, a convergence or finite-termination guarantee, and correct Rains-value normalization for Algorithm 1. (source-ambiguity)

Selected references

  • Non-asymptotic entanglement distillation, arXiv:1706.06221v3, https://arxiv.org/abs/1706.06221v3
27 thms2 active usersReviewed
Quantum Information·Captain: Goku

Capacities of Quantum Amplifier ChannelsResearch Paper

Motivation

Quantum amplifier channels are at the core of several physical processes. Not only do they model the optical process of spontaneous parametric down-conversion, but the transformation corresponding to an amplifier channel also describes the physics of the dynamical Casimir effect in superconducting circuits, the Unruh effect, and Hawking radiation. Here we study the communication capabilities of quantum amplifier channels. Invoking a recently established minimum output-entropy theorem for single-mode phase-insensitive Gaussian channels, we determine capacities of quantum-limited amplifier channels in three different scenarios. First, we establish the capacities of quantum-limited amplifier channels for one of the most general communication tasks, characterized by the trade-off between classical communication, quantum communication, and entanglement generation or consumption. Second, we establish capacities of quantum-limited amplifier channels for the trade-off between public classical communication, private classical communication, and secret key generation. Third, we determine the capacity region for a broadcast channel induced by the quantum-limited amplifier channel, and we also show that a fully quantum strategy outperforms those achieved by classical coherent detection strategies. In all three scenarios, we find that the capacities significantly outperform communication rates achieved with a naive time-sharing strategy.

This mission is the statement-level formalization of Capacities of Quantum Amplifier Channels (arXiv:1605.04922v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

3 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Equation (66), Appendix B (B9)–(B10): coherent-detection capacity regions (Equation (66), Appendix B (B9)–(B10): coherent-detection capacity regions, PDF p. 8). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

10 results of the paper are not stated yet, because the library lacks an interface they need:

  • Theorem 3: quantum dynamic capacity region (seed from abstract): Full Fock-space vacuum amplifier and independent operational net C,Q,E region (hard)
  • Unnumbered finite-energy quantum capacity, (34): Photon-constrained operational quantum capacity for the physical vacuum amplifier (hard)
  • Time-sharing comparisons: CQ/CE examples and ambiguous all-three-scenarios claim: Operational CQ/CE time-sharing comparisons at kappa=2, NS=200; a source-pinned private/public/key benchmark for the complete abstract claim (source-ambiguity)
  • Unnumbered monotonicity with amplifier gain, Figure 1(c,d): Operational CQ and CE slices at ordered gains with a common per-use budget (hard)
  • Theorem 4: noisy amplifier broadcast achievability: Noisy two-mode broadcast channel, coherent-state superposition ensemble and operational coding (hard)
  • Theorem 5: conditional noisy broadcast outer bound: Multimode spectral entropy, the noisy broadcast capacity and its full minimum-output-entropy premise (hard)
  • Corollary 6: exact quantum-limited broadcast capacity: Unconditional photon-constrained quantum-limited broadcast coding region (hard)
  • Unnumbered strict advantage over coherent detection, Figure 2(a): Unrestricted quantum broadcast capacity region at kappa=2, NS=5 (hard)
  • Unnumbered main result: private dynamic capacity, (75)–(77): Full complementary environment and independently defined secure net R,P,S coding region (hard)
  • Appendix C: qEPI outer bound for pure-loss dynamic capacity, (C11): Full Fock pure-loss channel, fixed vacuum complement, block spectral entropy and operational dynamic outer-region inclusion (hard)

Selected references

  • Capacities of Quantum Amplifier Channels, arXiv:1605.04922v3, https://arxiv.org/abs/1605.04922v3
6 thms2 active usersReviewed
Quantum Information·Captain: Goku

On Dimension Bounds for Auxiliary Quantum SystemsResearch Paper

Motivation

Expressions of several capacity regions in quantum information theory involve an optimization over auxiliary quantum registers. Evaluating such expressions requires bounds on the dimension of the Hilbert space of these auxiliary registers, for which no non-trivial technique is known; we lack a quantum analog of the Carath'{e}odory theorem. In this paper, we develop a new non-Carath'{e}odory-type tool for evaluating expressions involving a single quantum auxiliary register and several classical random variables. As we show, such expressions appear in problems of entanglement-assisted Gray-Wyner and entanglement-assisted channel simulation, where the question of whether entanglement helps in these settings is related to that of evaluating expressions with a single quantum auxiliary register. To evaluate such expressions, we argue that developing a quantum analog of the Carath'{e}odory theorem requires a better understanding of a notion which we call ``quantum conditioning." We then proceed by proving a few results about quantum conditioning, one of which is that quantum conditioning is strictly richer than the usual classical conditioning.

This mission is the statement-level formalization of On Dimension Bounds for Auxiliary Quantum Systems (arXiv:1207.3911v4). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

17 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Theorem 3(b): quantum conditioning is strictly richer than classical conditioning (Theorem 3(b): quantum conditioning is strictly richer than classical conditioning, PDF p. 10). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

3 results of the paper are not stated yet, because the library lacks an interface they need:

  • §1.2 Problems 1–4; §5: Exact finite-convex-hull stabilization and a bound uniform over all time-sharing output alphabets. (source-ambiguity)
  • Lemma 2: Compatibility of a family of conditional purifications with one Y-independent recovery POVM. (source-ambiguity)
  • Lemma 3: A specified relation between joint strong-typicality tolerance and conditional spectral-projector tolerance. (source-ambiguity)

Selected references

  • On Dimension Bounds for Auxiliary Quantum Systems, arXiv:1207.3911v4, https://arxiv.org/abs/1207.3911v4
25 thms2 active usersReviewed
Quantum Information·Captain: Goku

The private classical capacity and quantum capacity of a quantum channelResearch Paper

Motivation

A formula for the capacity of a quantum channel for transmitting private classical information is derived. This is shown to be equal to the capacity of the channel for generating a secret key, and neither capacity is enhanced by forward public classical communication. Motivated by the work of Schumacher and Westmoreland on quantum privacy and quantum coherence, parallels between private classical information and quantum information are exploited to obtain an expression for the capacity of a quantum channel for generating pure bipartite entanglement. The latter implies a new proof of the quantum channel coding theorem and a simple proof of the converse. The coherent information plays a role in all of the above mentioned capacities.

This mission is the statement-level formalization of The private classical capacity and quantum capacity of a quantum channel (arXiv:quant-ph/0304127v6). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

11 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Regularized private and key capacities of a cq wiretap channel (Theorem 1 / (6), PDF p. 4). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

2 results of the paper are not stated yet, because the library lacks an interface they need:

  • Proposition 7 / (51)–(53): A faithful operational entanglement-transmission definition for (52), including its source quantifiers or dimension-growth restriction; separately, the half-diamond capacity bridge. (source-ambiguity)
  • Section 6 computability claim: Definition of degradable cq W and a numerical complexity specification for Cp(W). (source-ambiguity)

Selected references

  • The private classical capacity and quantum capacity of a quantum channel, arXiv:quant-ph/0304127v6, https://arxiv.org/abs/quant-ph/0304127v6
20 thms2 active usersReviewed
Quantum Information·Captain: Goku

Zero-error communication under discrete-time Markovian dynamicsResearch Paper

Motivation

Consider an open quantum system with (discrete-time) Markovian dynamics. Our task is to store information in the system in such a way that it can be retrieved perfectly, even after the system is left to evolve for an arbitrarily long time. We show that this is impossible for classical (resp. quantum) information precisely when the dynamics is mixing (resp. asymptotically entanglement breaking). Furthermore, we provide tight universal upper bounds on the minimum time after which any such dynamics 'scrambles' the encoded information beyond the point of perfect retrieval. On the other hand, for dynamics that are not of this kind, we show that information must be encoded inside the peripheral space associated with the dynamics in order for it to be perfectly recoverable at any time in the future. This allows us to derive explicit formulas for the maximum amount of information that can be protected from noise in terms of the structure of the peripheral space of the dynamics.

This mission is the statement-level formalization of Zero-error communication under discrete-time Markovian dynamics (arXiv:2402.18703v3). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

37 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Eventual scrambling characterizes mixing and asymptotic entanglement breaking (Theorem 1.1, PDF p. 3). The milestones are the other numbered results, in the paper's order, each quoting the paper.

The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.

Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.

Deferred results

3 results of the paper are not stated yet, because the library lacks an interface they need:

  • Corollary C.9: Reviewed correction of the printed result (source-ambiguity)
  • §C.2, unnumbered five-dimensional example: Reviewed correction of the printed result (source-ambiguity)
  • Proposition C.12: Reviewed correction of the printed result (source-ambiguity)

Selected references

  • Zero-error communication under discrete-time Markovian dynamics, arXiv:2402.18703v3, https://arxiv.org/abs/2402.18703v3
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