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Campaigns (experimental)

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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.

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.

≥ 2.131125302137Formalized record→≥ 2.15Open frontier
11 provers on it19 of 20 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→≤ 1.9202796Open frontier
4 provers on it7 of 8 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.

≤ 2Formalized record
19 provers on it9 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.
≤ 12Formalized record→≤ 2Open frontier
8 provers on it14 of 15 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.

≤ 23Formalized record→≤ 5Open frontier
41 provers on it15 of 17 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

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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 ResearchStochastic Systems·Captain: mikedeng1

Privacy Management in Service Systems: Customer Control over Information Weakly Lowers Total Customer Surplus versus Full Disclosure under SPT Priority and Weakly Raises It under LPTResearch Paper

Motivation

Many service providers can infer how long a customer's request will take when the customer shares personal information. A customer who withholds that information may instead enter a queue as an unidentified request. Hu, Momot, and Wang study the resulting conflict between an individual's choice to disclose and the waiting times experienced by the whole customer population in a single-server system. Their comparison asks whether giving customers control over disclosure improves total customer surplus relative to a rule requiring full disclosure. The answer depends on which jobs the provider gives priority, even though the provider keeps the same priority order among identified and unidentified requests. Hu, Momot, and Wang, §3–4

The manuscript distinguishes shortest-processing-time priority (SPT), where the identified high-priority type has a shorter mean service time, from longest-processing-time priority (LPT), where it has a longer one. This distinction makes privacy control a queueing question as well as an information-choice question: withholding changes a request's priority class, so it changes waiting times for other customers. Theorem 1 gives the direction of the population-level comparison in both regimes. Hu, Momot, and Wang, Theorem 1, p. 15

Setting

Requests reach one server according to a Poisson process of rate λ\lambdaλ. A request has type HHH with probability α\alphaα and exponential mean service time 1/μ1/\mu1/μ, or type LLL with probability 1−α1-\alpha1−α and mean 1/(σμ)1/(\sigma\mu)1/(σμ). The rate parameter σ\sigmaσ is positive and differs from one. The average service rate of the combined population is μˉ=σμ/(1+α(σ−1))\bar\mu=\sigma\mu/(1+\alpha(\sigma-1))μˉ​=σμ/(1+α(σ−1)), and stability requires λ<μˉ\lambda<\bar\muλ<μˉ​. The manuscript also assumes a service reward RRR at least c/μˉc/\bar\muc/μˉ​, where ccc is the cost per unit of time spent in the system. These are the parameters of the two-type service model. Hu, Momot, and Wang, §3.2, p. 8

Each customer chooses whether to disclose before observing the request type. If the fraction that discloses is γ∈[0,1]\gamma\in[0,1]γ∈[0,1], disclosed type-HHH requests arrive at rate αγλ\alpha\gamma\lambdaαγλ, disclosed type-LLL requests at rate (1−α)γλ(1-\alpha)\gamma\lambda(1−α)γλ, and undisclosed requests at rate (1−γ)λ(1-\gamma)\lambda(1−γ)λ. The latter form a type-NNN class with a mixture of the two service-time distributions. The server uses preemptive priority in the fixed order H>N>LH>N>LH>N>L. For each class, WHW_HWH​, WNW_NWN​, and WLW_LWL​ denote its mean time in the system, including service. The values are determined by the three-class formulas in Online Appendix A.1. Hu, Momot, and Wang, §3.3–3.4 and Online Appendix A.1

An infinitesimal customer compares the utility of disclosure, Ud(γ,λ)=R−c(αWH+(1−α)WL)U_d(\gamma,\lambda)=R-c(\alpha W_H+(1-\alpha)W_L)Ud​(γ,λ)=R−c(αWH​+(1−α)WL​), with that of withholding, Uw(γ,λ)=R−cWNU_w(\gamma,\lambda)=R-cW_NUw​(γ,λ)=R−cWN​. The total customer surplus at population strategy γ\gammaγ is

CS(γ)=λ(γUd(γ,λ)+(1−γ)Uw(γ,λ)).CS(\gamma)=\lambda\bigl(\gamma U_d(\gamma,\lambda)+(1-\gamma)U_w(\gamma,\lambda)\bigr).CS(γ)=λ(γUd​(γ,λ)+(1−γ)Uw​(γ,λ)).

An equilibrium disclosure probability γ∗\gamma^*γ∗ is an endpoint supported by the appropriate strict utility comparison, or an interior point where the two utilities agree and their difference decreases nearby. The manuscript chooses the Pareto-dominant equilibrium when several exist. Hu, Momot, and Wang, Eq. (1), p. 10; equilibrium definition, p. 12; Eq. (9), Online Appendix p. 3

Formalization targets

Theorem 1: customer control versus full disclosure

Let CScontrol=CS(γ∗)CS_{\rm control}=CS(\gamma^*)CScontrol​=CS(γ∗) and CSdiscl=CS(1)=λUd(1,λ)CS_{\rm discl}=CS(1)=\lambda U_d(1,\lambda)CSdiscl​=CS(1)=λUd​(1,λ). The target is

σ<1⟹CScontrol≤CSdiscl,σ>1⟹CScontrol≥CSdiscl.\sigma<1\Longrightarrow CS_{\rm control}\le CS_{\rm discl},\qquad \sigma>1\Longrightarrow CS_{\rm control}\ge CS_{\rm discl}.σ<1⟹CScontrol​≤CSdiscl​,σ>1⟹CScontrol​≥CSdiscl​.

When γ∗<1\gamma^*<1γ∗<1 and α>0\alpha>0α>0, the corresponding inequality is strict. The first regime is SPT and the second is LPT: under the fixed ranking H>N>LH>N>LH>N>L, type HHH has the shorter mean service time exactly when σ<1\sigma<1σ<1. The comparison holds for any equilibrium satisfying the paper's equilibrium conditions, including its Pareto-dominant selection. Hu, Momot, and Wang, Theorem 1, p. 15

Supporting results

The mission includes Lemma 1's closed forms for UdU_dUd​ and UwU_wUw​, the closed form of CSCSCS and the auxiliary function Γ\GammaΓ in the proof of Lemma 4, its derivative and denominator-sign statements, and Lemma 4's monotonicity of CSCSCS on [0,1][0,1][0,1]. Those statements connect the queueing model to the social comparison without replacing the final claim by a special case. Hu, Momot, and Wang, Lemma 1, p. 12; Lemma 4, Online Appendix p. 3; proof of Lemma 4, Online Supplement p. 2

Significance

Theorem 1 identifies a precise direction for the welfare effect of control over request-type information in this model. Under SPT priority, giving customers control cannot raise total customer surplus above full disclosure; under LPT it cannot lower surplus below full disclosure. The result therefore ties the social effect of the same disclosure option to a service discipline and to the mix of request types. Its strict clauses identify when withholding produces a genuine difference rather than equality. Hu, Momot, and Wang, Theorem 1 and discussion, p. 15

The paper establishes the theorem and the supporting identities mathematically. Here the remaining task is to prove the Lean statements from the definitions of the queue's class parameters and mean times. The formal development can leave reusable algebraic interfaces for finite-class preemptive-priority queues and for checking stability and denominator conditions in rational queueing formulas. These definitions and statements currently compile as a local draft; they are not yet machine-checked proofs of the paper's results.

Difficulty

An individual disclosure choice moves a request between the middle priority class and one of the two extreme classes. The direct utility comparison does not by itself determine the direction of total surplus: each choice also changes the class workloads and the waiting times faced by other customers. Thus the endpoint comparison cannot be read off from the sign of Ud−UwU_d-U_wUd​−Uw​ at a single γ\gammaγ. The analysis must account for the full γ\gammaγ dependence of WHW_HWH​, WNW_NWN​, and WLW_LWL​, including the hyperexponential residual time of undisclosed requests. The algebra has several denominators whose sign matters, and a formula in the source proof has a boundary exception at γ=1\gamma=1γ=1. Hu, Momot, and Wang, Online Appendix A.1 and Online Supplement A.2

Formalization scope

Lean represents rates, costs, rewards, waits, disclosure probabilities, utilities, and surplus as real numbers. A generic three-class preemptive-priority interface stores mean service times, mean residual times, and workloads. The paper-specific model supplies the H, N, and L table from Online Appendix A.1, including the undisclosed class's hyperexponential residual time. It treats the resulting mean waiting times as formulas; it does not construct a stochastic queueing process. Lemma 1 then asserts genuine algebraic identities from those formulas, rather than following immediately from the definitions. Hu, Momot, and Wang, Online Appendix A.1

The standing assumptions retain σ>0\sigma>0σ>0, σ≠1\sigma\ne1σ=1, 0≤α≤10\le\alpha\le10≤α≤1, λ<μˉ\lambda<\bar\muλ<μˉ​, and R≥c/μˉR\ge c/\bar\muR≥c/μˉ​ from §3.2. They state μ>0\mu>0μ>0, λ>0\lambda>0λ>0, and c>0c>0c>0 explicitly because these are rates and a marginal cost, and because zero values would erase the strict comparisons. The theorem items restrict γ\gammaγ to [0,1][0,1][0,1] whenever using the waiting-time formulas. The auxiliary closed-form, derivative, and bracket items exclude α(1+σ)=1\alpha(1+\sigma)=1α(1+σ)=1, where the source's displayed second fraction is undefined as a real quotient. Lemma 4 and the goal include that parameter value. The derivative of Γ\GammaΓ is strictly negative on [0,1)[0,1)[0,1) and equals zero at 111; its strict decrease across the whole interval is stated separately. Hu, Momot, and Wang, §3.2 and Online Supplement A.2

Strict monotonicity of surplus requires 0<α<10<\alpha<10<α<1, since a population with only one service type has no type-mix effect. The goal's strict clause requires α>0\alpha>0α>0; at α=0\alpha=0α=0, a withholding equilibrium can have exactly the same surplus as full disclosure. The goal still quantifies over an equilibrium, rather than an arbitrary point of [0,1][0,1][0,1]. Contributions toward the queueing identities, rational-function sign conditions, monotonicity, and final comparison all serve this scope.

Selected references

  • Hu, M., Momot, R., and Wang, J., Privacy Management in Service Systems, submitted manuscript, draft of 12 February 2022; published in Manufacturing & Service Operations Management 24(5), 2022. SSRN 3628751.
8 thms2 active usersReviewed
🏆Completed
Operations ResearchOptimization·Captain: mikedeng1

The Effect of Multi-Channel and Omni-Channel Retailing on Physical Stores: A Higher Return Rate Calls for Fewer Physical Stores, a Broader Assortment, and Larger Stores When hr(1 − 2γ) > hoResearch Paper

Motivation

Retailers that sell through both a website and physical stores must choose how many stores to operate and which products to stock in them. Product returns change that decision: a customer who is uncertain about a product may inspect it in a store instead of purchasing it online and later returning it. Gao, Agrawal, and Cui study this tradeoff in a model where stores are uniformly spaced and every store carries the same assortment. Their Proposition 1 gives a counterintuitive comparison: when the product return rate rises, the optimal number of stores falls, while the range of products in each store grows. The present source is the authors' manuscript generated on 2020-12-25, with the relevant result on its p. 12 and proofs in its Online Appendix pp. 1–2; the journal pages are not used here.

Setting

Let III be a finite set of products. The retailer offers every product online and chooses a store count n≥0n\geq0n≥0 and a store assortment S⊆IS\subseteq IS⊆I. Stores are evenly located on a circle of circumference one, and each carries SSS. Product iii has a customer class of deterministic size Di>0D_i>0Di​>0. A fraction θ\thetaθ of this class is uninformed about its valuation. An uninformed customer dislikes the product with probability γ∈(0,1)\gamma\in(0,1)γ∈(0,1), the common return rate; a customer who dislikes an online purchase returns it. Informed customers know their valuations already.

The online hassle cost is ho≥0h_o\geq0ho​≥0, the return hassle cost is hr>0h_r>0hr​>0, and travel to a store costs t>0t>0t>0 per unit of distance. The retailer earns per-unit margin mim_imi​ and pays ki≥0k_i\geq0ki​≥0 for each return. Each carried product uses display area αi>0\alpha_i>0αi​>0 and inventory area proportional to store sales, with coefficient βi>0\beta_i>0βi​>0. A store also requires common area Ω0>0\Omega_0>0Ω0​>0; facility area costs ξ>0\xi>0ξ>0 per unit. These assumptions and the symmetric circular-city setting come from §§3.1–3.2 of the paper.

Let di,od_{i,o}di,o​ denote uninformed online demand. The paper's full-market-coverage assumption yields the four online and store demand functions in equations (5)–(6). One store has size Ω(γ,n,S)\Omega(\gamma,n,S)Ω(γ,n,S) from equation (8). The total expected profit is equation (9):

π(γ,n,S)=∑i∈I[mi((1−γ)θDi+(1−θ)Di)−kiγdi,o]−nξΩ(γ,n,S).\pi(\gamma,n,S)=\sum_{i\in I}\left[m_i\bigl((1-\gamma)\theta D_i+(1-\theta)D_i\bigr)-k_i\gamma d_{i,o}\right]-n\xi\Omega(\gamma,n,S).π(γ,n,S)=i∈I∑​[mi​((1−γ)θDi​+(1−θ)Di​)−ki​γdi,o​]−nξΩ(γ,n,S).

An optimal decision maximizes this profit over all n≥0n\geq0n≥0 and S⊆IS\subseteq IS⊆I. The paper relaxes the integrality of nnn on p. 11. The retailer prefers stores at rate γ\gammaγ if a decision with n>0n>0n>0 has strictly greater profit than the online-only decision. This reading distinguishes strict preference from a tie at the store-opening threshold.

Formalization targets

Main goal: Proposition 1

For 0<γ1<γ2<10<\gamma_1<\gamma_2<10<γ1​<γ2​<1, suppose stores are strictly preferred at both rates. For any optimal decisions (n1,S1)(n_1,S_1)(n1​,S1​) and (n2,S2)(n_2,S_2)(n2​,S2​), the goal is

n2<n1,S1⊆S2,∣S1∣≤∣S2∣,n_2<n_1,\qquad S_1\subseteq S_2,\qquad |S_1|\leq|S_2|,n2​<n1​,S1​⊆S2​,∣S1​∣≤∣S2​∣,

and, when hr(1−2γ2)>hoh_r(1-2\gamma_2)>h_ohr​(1−2γ2​)>ho​,

Ω(γ1,n1,S1)≤Ω(γ2,n2,S2).\Omega(\gamma_1,n_1,S_1)\leq\Omega(\gamma_2,n_2,S_2).Ω(γ1​,n1​,S1​)≤Ω(γ2​,n2​,S2​).

The goal includes the proposition's parenthetical equivalence hr(1−2γ)>ho  ⟺  γ<(hr−ho)/(2hr)h_r(1-2\gamma)>h_o\iff\gamma<(h_r-h_o)/(2h_r)hr​(1−2γ)>ho​⟺γ<(hr​−ho​)/(2hr​) and its necessary conditions γ<1/2\gamma<1/2γ<1/2 and ho<hrh_o<h_rho​<hr​. The size condition is evaluated at the larger rate, so it holds across the interval being compared.

Supporting targets: Lemma 1 and its proof

Lemma 1 identifies a threshold GGG for opening stores. Above it, the positive-store count is n∗(γ)=t/[2(γhr+ho)]n^*(\gamma)=t/[2(\gamma h_r+h_o)]n∗(γ)=t/[2(γhr​+ho​)], and the profitable assortment is specified by the inequality printed in the lemma. The milestones also record the authors' profit decrease beyond this count and the zero-or-turning-point bound. Further draft items state the incremental profit of each carried product, the increasing positive-store profit gap, the monotonicity of the closed forms, and the optimal-store-size expression in the Online Appendix. These are statements from the source rather than new targets selected by analogy.

Significance

The result links return behavior to two costly retail decisions at once. Stores can reduce online returns by letting uncertain customers inspect products, yet a higher return rate need not call for more locations. Within the model, fewer locations can be paired with a broader assortment, and the stores can become larger when the return and online hassle costs satisfy the stated condition. Without Proposition 1, the model's demand and profit equations alone do not establish the direction of these comparative statics. The paper also studies other hassle-cost changes and omni-channel services, but they use additional results and models.

The theorem is proved in the authors' manuscript. The remaining task here is a machine-checked development of its exact model, threshold, and comparative statics. The compiled mission items are statements with open proofs; a successful compile does not prove them. The demand and profit definitions, together with the lemmas about maximizing a piecewise expression over a continuous store count, can be reused when formalizing the paper's other sections.

Difficulty

The objective changes formula when all uninformed customers near a carried product switch to stores, and again when informed customers do. Therefore differentiating one expression for profit across all nnn does not justify a global optimum. At the store-opening threshold, the profit from stores can tie online-only profit; an interior count can then also be optimal. Product-selection ties can likewise produce more than one optimal assortment. A statement only about one selected closed form would not control every optimal decision and would miss the tie cases in Proposition 1.

Formalization scope

Products form a finite type, possibly empty, and assortments are finite subsets. The empty catalogue has no positive-store preference; a one-product parameter instance witnesses that strict store preference is possible. All monetary quantities and the relaxed store count are real numbers. The return rate is quantified separately in (0,1)(0,1)(0,1) so the same parameters can be compared at two rates. The bounds 0≤θ≤10\leq\theta\leq10≤θ≤1 and ki≥0k_i\geq0ki​≥0 spell out “fraction” and “handling cost” on pp. 6 and 9. No sign condition is imposed on the exogenous margins mim_imi​, which cancel from the decision comparison.

The source assumes sufficiently high customer valuations to guarantee full market coverage on p. 8. The Lean model begins with the resulting demand equations (5)–(6); it does not introduce valuations or prices from utility equations (1)–(4). The formulas retain 1/(2n)1/(2n)1/(2n) and the area expression divided by nnn; at n=0n=0n=0, Lean's zero-division convention gives zero store demand, while the total facility cost is multiplied by zero. The target always quantifies over actual profit maximizers. Proving only that t/[2(γhr+ho)]t/[2(\gamma h_r+h_o)]t/[2(γhr​+ho​)] decreases would leave the retailer's optimization claim untouched. Contributions to the source-backed milestones and the algebra connecting the two printed assortment criteria are in scope.

Selected references

  • Fei Gao, Vishal V. Agrawal, and Shiliang Cui, The Effect of Multi-Channel and Omni-Channel Retailing on Physical Stores, authors' manuscript (PDF of 2020-12-25), pp. 6–12 and Online Appendix pp. 1–2; published in Management Science, 2021. DOI: 10.1287/mnsc.2021.3968.
6 thms2 active usersReviewed
🏆Completed
Dynamic ProgrammingOperations ResearchProbability·Captain: mikedeng1

Profit or Growth? Dynamic Order Allocation in a Hybrid Workforce: The Variance of the Cross-Network Effect Decides Whether Market Thickness Benefits or Costs the SystemResearch Paper

Motivation

Many firms that run their own delivery or service workforce have started to operate a hybrid workforce: salaried employees serve part of the demand, while a crowd of independent freelancers on a platform owned by the same firm serves the rest. A firm in this position faces a recurring allocation question. Every order sent to the platform pays freelancers and so attracts more of them, which increases the platform's market thickness (the size of its freelancer pool) and with it the platform's own future demand. The same order, served in house, earns the firm's margin today. He and Goh study this trade-off between profit now and platform growth later, with data from the Vietnamese delivery company AhaMove (He & Goh, SSRN 3537700; published in Management Science, 2021, doi:10.1287/mnsc.2021.4177).

The question the mission formalizes is whether a thicker platform is worth having at all. The paper's answer, its Theorem 1, is that it depends on two numbers: the mean μ\muμ and, centrally, the variance σ2\sigma^2σ2 of the cross-network effect β\betaβ, the random number of platform orders generated per freelancer.

Setting

Time runs over periods t=1,…,Tt = 1, \dots, Tt=1,…,T. At the start of a period the platform has M>0M > 0M>0 freelancers and the firm faces D≥0D \ge 0D≥0 orders. The firm chooses a transfer quantity yyy with 0≤y≤D0 \le y \le D0≤y≤D and sends those orders to the platform. Customers pay p>0p > 0p>0 per order; an order served in house earns the firm rrr, with 0≤r<p0 \le r < p0≤r<p. The platform also receives its own demand βM\beta MβM, where β≥0\beta \ge 0β≥0 is random with Eβ2<∞\mathbb E\beta^2 < \inftyEβ2<∞. To serve the total load y+βMy + \beta My+βM it pays freelancers the payout ratio α=R(y+βM)/M\alpha = R(y + \beta M)/Mα=R(y+βM)/M, where R≥1R \ge 1R≥1 measures the inefficiency of freelancers relative to employees. The period profit is r(D−y)+p(1−α)(y+βM)r(D - y) + p(1 - \alpha)(y + \beta M)r(D−y)+p(1−α)(y+βM).

The state then moves to

M′=(ρ+δRβ)M+δRy,D′=ηD+θM+ϵ,M' = (\rho + \delta R\beta)M + \delta R y, \qquad D' = \eta D + \theta M + \epsilon,M′=(ρ+δRβ)M+δRy,D′=ηD+θM+ϵ,

with parameters ρ,δ,η≥0\rho, \delta, \eta \ge 0ρ,δ,η≥0 and shocks θ,ϵ\theta, \epsilonθ,ϵ that are square integrable and independent, with μθ=Eθ≥0\mu_\theta = \mathbb E\theta \ge 0μθ​=Eθ≥0. Future profits are discounted by γ∈[0,1]\gamma \in [0, 1]γ∈[0,1]. The value functions are VT+1=0V_{T+1} = 0VT+1​=0 and

Vt(M,D)=max⁡0≤y≤D r(D−y)+E[p(y+βM)(1−R(y+βM)M)]+γ E[Vt+1(M′,D′)].V_t(M,D) = \max_{0 \le y \le D}\ r(D-y) + \mathbb E\Big[p(y+\beta M)\Big(1 - \frac{R(y+\beta M)}{M}\Big)\Big] + \gamma\, \mathbb E\big[V_{t+1}(M', D')\big].Vt​(M,D)=0≤y≤Dmax​ r(D−y)+E[p(y+βM)(1−MR(y+βM)​)]+γE[Vt+1​(M′,D′)].

Write μ=Eβ\mu = \mathbb E\betaμ=Eβ, σ2=Var⁡β\sigma^2 = \operatorname{Var}\betaσ2=Varβ, μ0=(p−r)/(2pR)\mu_0 = (p - r)/(2pR)μ0​=(p−r)/(2pR) and Δ=γrμθp∑j≥0γjηj\Delta = \frac{\gamma r \mu_\theta}{p}\sum_{j \ge 0}\gamma^j\eta^jΔ=pγrμθ​​∑j≥0​γjηj (which is +∞+\infty+∞ when γη≥1\gamma\eta \ge 1γη≥1). Inside {μ>0,σ2>0}\{\mu > 0, \sigma^2 > 0\}{μ>0,σ2>0} the paper defines three disjoint regions: R1\mathcal R_1R1​ (high variance), σ2>μ/R−μ2+(μ0−μ)+2+Δ/R\sigma^2 > \mu/R - \mu^2 + (\mu_0 - \mu)_+^2 + \Delta/Rσ2>μ/R−μ2+(μ0​−μ)+2​+Δ/R; R2\mathcal R_2R2​ (low variance), σ2<μ/R−μ2\sigma^2 < \mu/R - \mu^2σ2<μ/R−μ2; and R3\mathcal R_3R3​ (moderate variance), strictly between the two bounds. Market thickness benefits the system in period ttt if Vt(M,D)V_t(M, D)Vt​(M,D) is increasing in MMM for every fixed DDD, and is costly if it is decreasing; both in the weak sense.

Formalization targets

Goal: Theorem 1 (p. 15)

(μ,σ)∈R1  ⟹  thickness is costly in every period t∈{1,…,T},(μ,σ)∈R2  ⟹  thickness benefits the system in every period,(μ,σ)∈R3  ⟹  ∃ 1≤τ1≤τ2≤T: benefit for t<τ1, costly as M→∞ for t≥τ2,\begin{aligned} (\mu,\sigma)\in\mathcal R_1 &\implies \text{thickness is costly in every period } t\in\{1,\dots,T\},\\ (\mu,\sigma)\in\mathcal R_2 &\implies \text{thickness benefits the system in every period},\\ (\mu,\sigma)\in\mathcal R_3 &\implies \exists\, 1\le\tau_1\le\tau_2\le T:\ \text{benefit for } t<\tau_1,\ \text{costly as } M\to\infty \text{ for } t\ge\tau_2, \end{aligned}(μ,σ)∈R1​(μ,σ)∈R2​(μ,σ)∈R3​​⟹thickness is costly in every period t∈{1,…,T},⟹thickness benefits the system in every period,⟹∃1≤τ1​≤τ2​≤T: benefit for t<τ1​, costly as M→∞ for t≥τ2​,​

and τ1=τ2\tau_1 = \tau_2τ1​=τ2​ when μ>μ0\mu > \mu_0μ>μ0​. "Costly as M→∞M \to \inftyM→∞" means that for every D>0D > 0D>0, Vt(⋅,D)V_t(\cdot, D)Vt​(⋅,D) is decreasing on some tail [M0,∞)[M_0, \infty)[M0​,∞).

Milestones

The appendix proves the theorem through a structural result and three lemmas, which are the milestones, in attack order:

  • Proposition 1: VtV_tVt​ is jointly concave in (M,D)(M, D)(M,D).
  • Lemma 1(c): the optimal transfer is ytU∧Dy^U_t \wedge DytU​∧D for the threshold ytUy^U_tytU​ of (14).
  • Lemma 1(d): bounds on ∂1Vt+1\partial_1 V_{t+1}∂1​Vt+1​ give the linear bounds (15) on ytUy^U_tytU​.
  • Lemma 1(b): the right partial derivatives of VtV_tVt​ are uniformly bounded.
  • Lemma 1(a): the envelope formulas (13).
  • Lemma 2: the limits K(t)=lim⁡M→∞∂1VtK(t) = \lim_{M\to\infty}\partial_1V_tK(t)=limM→∞​∂1​Vt​ and L(t)=lim⁡M→0∂2VtL(t) = \lim_{M\to 0}\partial_2V_tL(t)=limM→0​∂2​Vt​, and the bounds ∂1Vt≥K(t)\partial_1V_t \ge K(t)∂1​Vt​≥K(t), ∂2Vt≥L(t)\partial_2V_t \ge L(t)∂2​Vt​≥L(t).
  • Lemma 3(a)–(b): the explicit lower bound K(t)≥G(t)K(t) \ge G(t)K(t)≥G(t) of (17), and the single-switch property of GGG.
  • Lemma 3(c), with the hypothesis μ0≤μ\mu_0 \le \muμ0​≤μ: once (μ0−μ)+γδ2pG(t+1)<0(\mu_0 - \mu) + \frac{\gamma\delta}{2p}G(t+1) < 0(μ0​−μ)+2pγδ​G(t+1)<0, the optimal transfer is 000 and ∂1Vs=G(s)\partial_1V_s = G(s)∂1​Vs​=G(s), ∂2Vs=L(s)\partial_2V_s = L(s)∂2​Vs​=L(s) from then on.

Significance

The theorem replaces the intuition that a larger freelancer pool is always an asset with a criterion that a firm can estimate. When β\betaβ is very volatile, matching supply to a random platform demand is expensive, because the wage bill is quadratic in the load, and a thicker market only amplifies that cost; when β\betaβ is stable, thickness pays in every period. In the moderate regime the value of thickness changes sign once over the horizon, which is what drives the paper's later results on the structure of the optimal transfer policy (Proposition 3) and on the gap between the dynamic and the myopic policy (Theorem 2).

The result is proved in the paper. It has no machine-checked proof. Formalizing it adds a checked model of a finite-horizon stochastic dynamic program with a continuous two-dimensional state, concavity of value functions under partial maximization, envelope formulas with right derivatives, and an explicit backward recursion for the bound GGG. The formalization also records two printed slips that it corrects (see Formalization scope).

Difficulty

The obvious argument is a backward induction on the sign of ∂1Vt\partial_1 V_t∂1​Vt​, read off the envelope formula (13). That step does not close by itself: the formula contains the optimal transfer yt∗y^*_tyt∗​, its multiplier and expectations of the next period's partial derivatives at random states, so the induction needs a priori bounds on the derivatives, monotone limits as M→∞M \to \inftyM→∞ and M→0M \to 0M→0, and exchanges of limits with expectations. The value functions are only concave, so all derivatives are one-sided, and the optimal decision can sit on the constraint y=Dy = Dy=D. Part (c) needs, in addition, an explicit lower bound GGG on the asymptotic slope and a proof that GGG switches sign at most once.

Formalization scope

All statements share one definition, HybridOrderAlloc.Thickness.Model. The data are a structure Sys Ω (a measure PPP on Ω\OmegaΩ, shocks β,θ,ϵ:Ω→R\beta, \theta, \epsilon : \Omega \to \mathbb Rβ,θ,ϵ:Ω→R, real parameters p,r,R,ρ,δ,η,γp, r, R, \rho, \delta, \eta, \gammap,r,R,ρ,δ,η,γ and T∈NT \in \mathbb NT∈N) and a predicate Sys.Standing with the page's assumptions. Conventions committed to:

  • One shock vector serves every period, since the shocks are i.i.d. across periods and (5) only uses their one-period law. The joint law of β\betaβ and (θ,ϵ)(\theta, \epsilon)(θ,ϵ) is left free, as on the page.
  • VtV_tVt​ is the recursion (5) itself, defined by the number of periods to go, with the page's maximum written as a supremum over [0,D][0, D][0,D]. It is defined for M>0M > 0M>0, D≥0D \ge 0D≥0; all conclusions are stated on M>0M > 0M>0, D>0D > 0D>0 as in the paper.
  • ∂1Vt\partial_1 V_t∂1​Vt​, ∂2Vt\partial_2 V_t∂2​Vt​ are right partial derivatives, as in the paper's Notation paragraph. Expectations are Bochner integrals and σ2\sigma^2σ2 is Mathlib's variance.
  • "Increasing" and "decreasing" are weak (MonotoneOn, AntitoneOn). GGG is indexed by integers.

Hypotheses added to the page, each disclosed in the statements: r≥0r \ge 0r≥0 (Theorem 1 is false for r<0r < 0r<0, because Δ<0\Delta < 0Δ<0 then puts points where thickness pays into R1\mathcal R_1R1​); ρ+δRβ>0\rho + \delta R\beta > 0ρ+δRβ>0, θ≥0\theta \ge 0θ≥0, ϵ≥0\epsilon \ge 0ϵ≥0 almost surely (so the next state stays in the domain of Vt+1V_{t+1}Vt+1​ for every feasible yyy, which the page takes for granted); T≥1T \ge 1T≥1; and μ0≤μ\mu_0 \le \muμ0​≤μ in Lemma 3(c) alone (the printed lemma fails for μ<μ0\mu < \mu_0μ<μ0​).

VtV_tVt​ is never a free parameter constrained by a Bellman hypothesis, and never a closed formula. Square integrability of β,θ,ϵ\beta, \theta, \epsilonβ,θ,ϵ is assumed, so no integral takes a junk value. The regions carry the guard γη<1\gamma\eta < 1γη<1 wherever Δ\DeltaΔ appears, so a divergent series cannot be read as 000.

A complete development needs: concavity of a partial maximum over a convex graph, one-sided envelope theorems, dominated convergence for the derivative limits, and finite geometric sums. The concavity and envelope steps are reusable for other dynamic programs with continuous states. Proofs of any milestone are welcome, as are sharper variants that remove the added well-posedness hypotheses.

Selected references

  • E. J. He and J. Goh, Profit or Growth? Dynamic Order Allocation in a Hybrid Workforce, Management Science, 2021; preprint SSRN 3537700 (2020). https://ssrn.com/abstract=3537700, https://doi.org/10.1287/mnsc.2021.4177
  • P. Milgrom and I. Segal, Envelope Theorems for Arbitrary Choice Sets, Econometrica 70(2), 583–601, 2002. https://doi.org/10.1111/1468-0262.00296
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Actuarial ScienceOperations ResearchProbability·Captain: mikedeng1

On the Profitability of Selfish Blockchain Mining Under Consideration of Ruin: Closed-Form Expected Surplus of a Selfish Miner under Ruin up to an Exponential Time HorizonResearch Paper

Motivation

A blockchain miner pays for electricity and equipment while block rewards arrive at irregular times. A strategy that raises the average reward can still expose a miner with limited capital to ruin before those rewards arrive. Albrecher and Goffard study this tension for a simplified selfish mining strategy in which the miner temporarily withholds a discovered block. Their model connects the block discovery process to a dual risk process: capital falls continuously as costs accrue and jumps upward when the miner collects block rewards. The quantity of interest is the miner's expected remaining capital at a random evaluation time, counting paths that have already reached ruin as zero. The paper derives a closed expression for this quantity when the miner begins with no withheld block. Albrecher and Goffard, arXiv:2010.12577v1, §§2–3.

Setting

Network blocks are discovered at Poisson rate λ>0\lambda>0λ>0. The miner has a share p∈(0,1)p\in(0,1)p∈(0,1) of computing power, pays operating costs at rate c>0c>0c>0, and receives b>0b>0b>0 per block for which the strategy earns a reward. On each discovery, ξ\xiξ records whether the miner found the block. If the miner has produced a fork and another participant finds the next block, ζ\zetaζ records whether that participant extends the miner's branch; its probability is q∈[0,1]q\in[0,1]q∈[0,1].

The state Zk∈{0,1,0∗}Z_k\in\{0,1,0^*\}Zk​∈{0,1,0∗} just before discovery k+1k+1k+1 records an empty buffer, one withheld block, or a public fork. From state 000, the miner withholds a newly found block and earns nothing. From state 111, a further miner discovery pays for two blocks and returns to 000; a competing discovery creates a fork. From 0∗0^*0∗, the next discovery resolves the fork and returns to 000. It pays two rewards if the miner finds the block, one reward if another miner extends the miner's branch, and no reward otherwise. These cases define the reward count fff and the surplus

Rs=u−cs+b∑k=0Ns−1f(Zk,ξk+1,ζk+1),R_s=u-cs+b\sum_{k=0}^{N_s-1} f(Z_k,\xi_{k+1},\zeta_{k+1}),Rs​=u−cs+bk=0∑Ns​−1​f(Zk​,ξk+1​,ζk+1​),

where u≥0u\ge0u≥0 is initial capital and NsN_sNs​ is the number of network discoveries by time sss. The ruin time is τu=inf⁡{s≥0:Rs=0}\tau_u=\inf\{s\ge0:R_s=0\}τu​=inf{s≥0:Rs​=0}. For initial state zzz, the fixed-horizon value is Vz(u,s)=E[Rs1{τu>s}]V_z(u,s)=\mathbb E[R_s\mathbf1_{\{\tau_u>s\}}]Vz​(u,s)=E[Rs​1{τu​>s}​]. The paper replaces a fixed horizon by an independent exponential time TTT of mean t>0t>0t>0 and defines V^z(u,t)=E[Vz(u,T)]\widehat V_z(u,t)=\mathbb E[V_z(u,T)]Vz​(u,t)=E[Vz​(u,T)]. Thus the exponential law has rate 1/t1/t1/t. Source, equations (15), (16), and (19).

Formalization targets

Closed-form value

The goal is Theorem 3.1 for the initially empty buffer. Let C,D1,…,D7C,D_1,\ldots,D_7C,D1​,…,D7​ be the parameter expressions in the paper's equation (22). Let ρ1\rho_1ρ1​ and ρ2±iρ3\rho_2\pm i\rho_3ρ2​±iρ3​ be precisely the roots with negative real part of

(D1ρ+D2)e2bρ+D3ebρ=D4ρ3+D5ρ2+D6ρ+D7.(D_1\rho+D_2)e^{2b\rho}+D_3e^{b\rho}=D_4\rho^3+D_5\rho^2+D_6\rho+D_7.(D1​ρ+D2​)e2bρ+D3​ebρ=D4​ρ3+D5​ρ2+D6​ρ+D7​.

For A1,A2,A3A_1,A_2,A_3A1​,A2​,A3​ satisfying the corrected boundary system (23), the target is, for all u≥0u\ge0u≥0,

V^0(u,t)=A1eρ1u+eρ2u(A2cos⁡(ρ3u)+A3sin⁡(ρ3u))+u+C.\widehat V_0(u,t)=A_1e^{\rho_1u}+e^{\rho_2u}\bigl(A_2\cos(\rho_3u)+A_3\sin(\rho_3u)\bigr)+u+C.V0​(u,t)=A1​eρ1​u+eρ2​u(A2​cos(ρ3​u)+A3​sin(ρ3​u))+u+C.

The paper prints the third right-hand side of (23) as −2b−C−1/(ct)-2b-C-1/(ct)−2b−C−1/(ct). Its boundary condition (33), together with its own coefficients (24), requires −(λ2p2/c2)(2b+C)−1/(ct)-(\lambda^2p^2/c^2)(2b+C)-1/(ct)−(λ2p2/c2)(2b+C)−1/(ct). The mission states this correction explicitly. Source, Theorem 3.1 and equations (23), (24), (33).

Milestones

The three curated targets are the corrected advanced differential system (29) for the three starting states; Lemma A.1, which counts three characteristic roots in the left half-plane when 0<p,q<10<p,q<10<p,q<1; and the explicit function in (39)–(40), including its corrected boundary equations. These are statements made in Appendix A and used in the discussion of Theorem 3.1. The root-count lemma has the narrower hypothesis 0<q<10<q<10<q<1 that the authors print; the main result permits q=0q=0q=0 and q=1q=1q=1 while specifying the root set. Source, Appendix A.

Significance

The formula gives expected remaining capital for a specific block-withholding policy while accounting for the event of ruin before the evaluation horizon. It allows the model's cost rate, reward size, hash share, connectivity, and initial reserve to be compared through the same value function. The result addresses the limited-capital question that an average revenue rate alone does not answer. Its use is within this simplified strategy and the paper's Poisson and independent-mark assumptions. Source, §§3–4.

The result is presented in the paper, but a machine-checked proof of this corrected statement is still to be supplied. A complete development would establish the expectation's measurability and integrability, the differential properties of the three state-dependent value functions, the complex root count, and the identification of the explicit function with the expectation. The stochastic model and its value function can also support separate formalizations of the paper's ruin-probability and honest-miner results.

Difficulty

The reward at a discovery depends on withheld-block state, so the surplus alone does not describe the next reward. The value functions for all three states are coupled, and the resulting differential equations evaluate the empty-buffer function at larger reserves u+bu+bu+b and u+2bu+2bu+2b. Those advanced terms prevent a direct application of ordinary differential-equation uniqueness results. The root count is a statement about a transcendental complex equation, and its left-half-plane roots must be isolated exactly.

Appendix A says that it constructs a solution of the advanced equation and assumes uniqueness, observing that simulations can check the result. That assumption leaves an identification step between the displayed candidate and the stochastic expectation that the paper does not prove. It remains part of the goal, without an invented source milestone. Source, p. 25.

Formalization scope

Lean represents the network process through independent exponential interarrival times of rate λ\lambdaλ and independent Bernoulli marks. Marks begin at index zero in code, corresponding to the paper's first block at index one. The state transition and reward map encode the cases of (16). The ruin time is extended nonnegative, so an empty set of ruin times has infimum ∞\infty∞. On the null event of infinitely many arrivals in finite time, the cardinality-based block count has Lean's default value zero; the model law excludes that event almost surely.

The horizon average uses the first expression in (19), integrating Vz(u,s)V_z(u,s)Vz​(u,s) against the exponential measure of rate 1/t1/t1/t. The expected surplus must be obtained from this stochastic construction; defining it by the closed formula or by a differential equation would erase the target. The roots and coefficients are constrained by the characteristic equation and corrected boundary system, and integral defaults on nonintegrable inputs cannot establish the result. No net-profit condition is imposed on Theorem 3.1.

The paper-specific definitions, the three curated milestones, and the main theorem are open to contributions. General infrastructure for marked Poisson processes, extended ruin times, integration of stopped surplus, and complex root counting would be reusable beyond this case. The four printed discrepancies affecting (23), (29), (31), and (40) are recorded in the local moderation notes; this mission's Lean statements use the mathematically corrected forms.

Selected references

  • Hansjörg Albrecher and Pierre-Olivier Goffard, On the Profitability of Selfish Blockchain Mining Under Consideration of Ruin, arXiv:2010.12577v1, 2020; published in Operations Research, 2022. arXiv preprint
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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
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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
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🏆Completed
Algorithmic Game TheoryOperations Research·Captain: mikedeng1

Implementing Environmental and Social Responsibility Programs in Supply Networks Through Multiunit Bilateral Negotiation: A Log-Cost Shortest Path Tree Maximizes the Retailer's GainResearch Paper

Motivation

Retailers sometimes ask every supplier in a production network to meet a common environmental or social responsibility standard. A program can fail to produce its expected value if even one firm declines to participate. The retailer therefore needs a way to pass commitments and payments through the network, including to suppliers with whom it has no direct purchase contract. Feng, Li, Lu, and Shanthikumar model that choice as a network of simultaneous bilateral negotiations and ask which negotiation links a retailer should use. Their examples distinguish direct engagement with distant suppliers from delegating those negotiations to intermediate firms. Feng et al., accepted manuscript, §§1, 3–4.2.

The paper's target is a structural decision. A retailer can arrange the same firms into different negotiation trees; those trees alter how much of a fixed total ESR surplus the retailer retains. The result formalized here identifies a preferred tree using path costs derived from bargaining power. The published article appeared in Management Science in 2021; this mission follows the authors' January 2021 accepted manuscript, whose theorem numbering and printed pages are the source for the statements below. Feng et al., accepted manuscript, pp. 9–21.

Setting

The firms are N={0,1,…,n}N=\{0,1,\ldots,n\}N={0,1,…,n}, with retailer 000. In the material network AAA, an arc (i,j)(i,j)(i,j) means downstream firm iii buys goods or services from upstream firm jjj. The ESR network AESRA^{\mathrm{ESR}}AESR also permits (i,j)(i,j)(i,j) when there is a directed material path from iii to jjj. Thus a retailer can negotiate directly with a distant upstream supplier even when an intermediate firm handles the material purchase. A feasible implementation structure TTT is a rooted tree of ESR arcs spanning all firms: every supplier has exactly one downstream parent, and every firm's parent chain reaches retailer 000. Feng et al., §3, pp. 9, 12–13, display (1).

Every firm must invest to create the program's revenue RRR. Firm iii incurs cost cic_ici​, and universal participation leaves positive total surplus Π=R−∑i∈Nci>0\Pi=R-\sum_{i\in N}c_i>0Π=R−∑i∈N​ci​>0. In a negotiation on (i,j)(i,j)(i,j), downstream firm iii has bargaining power θi,j\theta_{i,j}θi,j​ and upstream firm jjj has power 1−θi,j1-\theta_{i,j}1−θi,j​. Their relative bargaining power is ρi,j=(1−θi,j)/θi,j\rho_{i,j}=(1-\theta_{i,j})/\theta_{i,j}ρi,j​=(1−θi,j​)/θi,j​. The route from the retailer to firm vvv in TTT is Pv(T)P_v(T)Pv​(T). Feng et al., §3, pp. 10–12; §4.1, pp. 16–17.

A payment wi,jw_{i,j}wi,j​ goes from downstream iii to upstream jjj. A firm's gain is its receipts less its payments and investment cost, plus RRR if it is the retailer and all firms invest. A Nash–Nash equilibrium is a profile of arc payments in which each parent and child bargain over their own payment with the other payments fixed. They maximize their weighted Nash product subject to both gains being nonnegative; a negotiation breakdown generates zero disagreement gain. Feng et al., §4.1, pp. 15–17, displays (4)–(6).

Formalization targets

Equilibrium payments and gains

For a feasible TTT, Theorem 1 specifies the payment on each arc at universal participation. Corollary 1 then gives the retailer's gain and each supplier's gain in terms of products along root routes. In particular,

Γ(T)=∑v∈N∖{0}∏a∈Pv(T)ρa,π0(T,1)=Π1+Γ(T).\Gamma(T)=\sum_{v\in N\setminus\{0\}}\prod_{a\in P_v(T)}\rho_a, \qquad \pi_0(T,\mathbf 1)=\frac{\Pi}{1+\Gamma(T)}.Γ(T)=v∈N∖{0}∑​a∈Pv​(T)∏​ρa​,π0​(T,1)=1+Γ(T)Π​.

These are separate milestones because a formula for one payment does not by itself describe the network-wide gain distribution. Feng et al., p. 17, Theorem 1 and Corollary 1, displays (7)–(8).

Retailer preference and shortest path tree

The retailer maximizes its equilibrium gain by minimizing Γ(T)\Gamma(T)Γ(T) over feasible structures, as stated before and in display (9). Give each ESR arc the real cost di,j=log⁡ρi,jd_{i,j}=\log\rho_{i,j}di,j​=logρi,j​. A shortest path tree T∗T^*T∗ has a minimum-cost route from 000 to every supplier among simple directed ESR routes. Theorem 2 asserts

Γ(T∗)≤Γ(T)for every feasible T,π0(T,1)≤π0(T∗,1)at Nash–Nash equilibrium.\Gamma(T^*)\le\Gamma(T) \quad\text{for every feasible }T, \qquad \pi_0(T,\mathbf 1)\le\pi_0(T^*,\mathbf 1) \quad\text{at Nash–Nash equilibrium}.Γ(T∗)≤Γ(T)for every feasible T,π0​(T,1)≤π0​(T∗,1)at Nash–Nash equilibrium.

The first inequality is Theorem 2 as printed. The second records the retailer-gain interpretation immediately preceding display (9) and the paper's stated motivation for the structure result. Feng et al., §4.2, pp. 20–21, display (9), Theorem 2.

Significance

The theorem replaces a choice among potentially many feasible negotiation trees with a recognizable network object. It characterizes a retailer-preferred way to assign negotiations across tiers, while Corollary 1 also reports how each firm's share changes with the route linking it to the retailer. The paper uses the structure result to discuss delegation and engagement in supplier networks; its later extensions consider additional investment and negotiation settings. Feng et al., §§4.2–5.

The paper result is proved in its online appendix, which is not part of the held manuscript. The present mission supplies precise Lean statements for the network, bargaining equilibrium, gain allocation, and tree optimum. A local prior-art search found no published formalization of this particular network equilibrium or shortest-path-tree conclusion. Completing the mission would add machine-checked proofs of these statements and definitions that could be reused for other bargaining networks with a common surplus.

Difficulty

The arc costs are additive logarithms, but Γ(T)\Gamma(T)Γ(T) is a sum of multiplicative path weights. The paper explicitly warns that the total log cost of a shortest path tree is not the objective in display (9). A direct minimum-total-tree-cost argument therefore does not establish Theorem 2. At the bargaining layer, each payment affects the gains of two firms while the other negotiations remain in force; an independent two-person bargaining calculation does not yet establish a simultaneous network equilibrium. Feng et al., §4.1, pp. 16–17; §4.2, p. 20.

Formalization scope

Lean represents firms as Fin (n + 1), so retailer 000 exists even when n=0n=0n=0. Material arcs are a directed relation, and ESR arcs are its nonempty-path transitive closure. A parent map represents a feasible implementation tree; the retailer is pinned as its own parent, and that value never contributes a payment. Parent iteration must reach 000 from every firm. The tree's root route and subtree are derived from this map, rather than supplied as unrelated data. Payments are indexed by the supplier endpoint because every supplier has exactly one parent arc. Gains, powers, payments, and path costs are real-valued.

The manuscript permits θi,j∈[0,1]\theta_{i,j}\in[0,1]θi,j​∈[0,1], but the formal statements assume 0<θi,j<10<\theta_{i,j}<10<θi,j​<1 on ESR arcs. This disclosed restriction ensures the ratio and its logarithm retain their intended mathematical meaning; Lean assigns default values to division by zero and logarithms outside their positive domain. The manuscript's opposing-power identity θj,i=1−θi,j\theta_{j,i}=1-\theta_{i,j}θj,i​=1−θi,j​ is required on ESR arcs, including when material cycles permit both arc orientations. Investment costs are nonnegative, and Π>0\Pi>0Π>0. The formalization uses the manuscript's description of a rooted spanning tree; the in-degree condition printed in display (1) by itself also admits cycles disconnected from the retailer. Shortestness compares a tree route with every simple directed ESR route, so it does not define a shortest path tree by the desired Γ\GammaΓ inequality. The Nash comparison ranges only over payment deviations for which both firms' gains are nonnegative.

The definition layer needs finite directed paths, root-route products, contingent gains, and weighted Nash products. Reusable contributions include a rooted parent-map representation and a shortest-path-tree predicate for real arc costs. Solvers may contribute proofs and supporting lemmas for the three source milestones or the goal theorem; the additional delegation, Shapley, and extension results elsewhere in the paper are outside this mission.

Selected references

  • Q. Feng, C. Li, M. Lu, and J. G. Shanthikumar, Implementing Environmental and Social Responsibility Programs in Supply Networks Through Multiunit Bilateral Negotiation, accepted manuscript, January 2021; Management Science, 2021. SSRN 3309518; doi:10.1287/mnsc.2021.4034.
5 thms2 active usersReviewed
🏆Completed
Quantum Information·Captain: Goku

Singular value decomposition and matrix reorderings in quantum information theoryResearch Paper

Motivation

We review Schmidt and Kraus decompositions in the form of singular value decomposition using operations of reshaping, vectorization and reshuffling. We use the introduced notation to analyse the correspondence between quantum states and operations with the help of Jamiolkowski isomorphism. The presented matrix reorderings allow us to obtain simple formulae for the composition of quantum channels and partial operations used in quantum information theory. To provide examples of the discussed operations we utilize a package for the Mathematica computing system implementing basic functions used in the calculations related to quantum information theory.

This mission is the statement-level formalization of Singular value decomposition and matrix reorderings in quantum information theory (arXiv:1011.1585v2). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

12 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Schmidt decomposition of a bipartite pure state (Theorem 2, Eq.(19), 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:

  • Example 4, Eqs.(54)–(56): A parameter-consistent singular system and canonical Kraus family for Example 4, Eqs.(54)–(56). (source-ambiguity)
  • Definition 9, Eq.(58): A trace-preserving Kraus criterion consistent with the action Psi(rho)=sum A_i rho A_i dagger. (source-ambiguity)

Selected references

  • Singular value decomposition and matrix reorderings in quantum information theory, arXiv:1011.1585v2, https://arxiv.org/abs/1011.1585v2
22 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
35 thms2 active usersReviewed
Quantum Information·Captain: Goku

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
18 thms2 active usersReviewed
Quantum Information·Captain: Goku

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
🏆Completed
Algorithmic Game TheoryGraph TheoryOperations Research·Captain: mikedeng1

The Buck-Passing Game: Every Deterministic Buck-Passing Game Has a Prior-Free Pure Nash EquilibriumResearch Paper

Why the game matters

In a buck-passing game, each participant chooses who will receive a task, burden, or token next. The eventual share of time spent holding it depends on every participant's choice. This makes a small network into a game: a local change of one outgoing edge can alter the long-run burden across an entire part of the network. Cominetti, Quattropani, and Scarsini study this setting in The Buck-Passing Game, including deterministic and stochastic versions. The deterministic result targeted here says that players can choose their outgoing edges without knowing where the buck will start and still reach a pure Nash equilibrium.

That independence from the starting distribution matters because an initial probability law can be unknown or disputed. A Nash equilibrium found for one chosen law may cease to be an equilibrium under another. The paper calls a profile that works for every law a prior-free Nash equilibrium. Its existence is the subject of Theorem 2 on p. 10 of arXiv:1808.03206v4.

The deterministic setting

Start with a finite directed graph G=(V,E)G=(V,E)G=(V,E) without loops. Each vertex iii is a player and has a nonempty set Ni+N_i^+Ni+​ of outgoing neighbors. Player iii chooses one neighbor si∈Ni+s_i\in N_i^+si​∈Ni+​; the collection s=(si)i∈Vs=(s_i)_{i\in V}s=(si​)i∈V​ is a strategy profile. Once these choices are fixed, the graph becomes a functional graph: from each vertex there is exactly one selected outgoing edge, and the buck moves according to the map fs(i)=sif_s(i)=s_ifs​(i)=si​.

At time zero, Nature places the buck at a vertex drawn from a probability distribution μ\muμ on VVV. At time t≥1t\geq1t≥1, the buck is at fst(j)f_s^t(j)fst​(j) if it started at jjj. The cost ci(s)c_i(s)ci​(s) of player iii is the expected limiting fraction of positive times for which iii holds it. Players minimize their own costs. The definition follows equation (3) on p. 6: for each possible start jjj, count visits at times 1,…,T1,\ldots,T1,…,T, divide by TTT, take the limit, and average the resulting value with weights μj\mu_jμj​.

Every orbit on a finite functional graph eventually enters a directed cycle. The vertices whose orbits enter the same cycle form its basin, called a unicycle in the paper. The cycles CsℓC_s^\ellCsℓ​ are pairwise disjoint, and their basins AsℓA_s^\ellAsℓ​ partition the vertices. Equation (6) on p. 7 says that a player outside a cycle has zero long-run cost, while a player on cycle CsℓC_s^\ellCsℓ​ has cost μ(Asℓ)/∣Csℓ∣\mu(A_s^\ell)/|C_s^\ell|μ(Asℓ​)/∣Csℓ​∣. A unilateral change is profitable when it strictly lowers the changing player's cost; a profile with no profitable change is a pure Nash equilibrium. Definitions 1–3 and equations (3)–(6) fix these terms.

Formalization targets

The main target is Theorem 2. The order of its quantifiers is essential: one profile must work for every initial probability distribution. Writing Δ(V)\Delta(V)Δ(V) for the probability distributions on VVV, the claim is

∃s∈∏i∈VNi+∀μ∈Δ(V)∀i∈V∀x∈Ni+,ci(s)≤ci(x,s−i).\exists s\in\prod_{i\in V}N_i^+\quad\forall\mu\in\Delta(V)\quad\forall i\in V\quad\forall x\in N_i^+,\qquad c_i(s)\leq c_i(x,s_{-i}).∃s∈i∈V∏​Ni+​∀μ∈Δ(V)∀i∈V∀x∈Ni+​,ci​(s)≤ci​(x,s−i​).

The proposed milestones match the claims leading up to this result in §3.1 of the paper. A component-wise minimizer of a generalized ordinal potential is a Nash equilibrium. Proposition 1 guarantees an equilibrium for a finite generalized ordinal potential game and also for the compact, lower semicontinuous case. Equation (6) identifies costs from the limiting visit frequencies. The p. 9 classification describes the two types of profitable deviation. Theorem 1 supplies a generalized ordinal potential that depends only on the selected cycles:

Ψ(s)=∑ℓ=1M(s)(∣V∣−∣Csℓ∣),ci(x,s−i)<ci(s)  ⟹  Ψ(x,s−i)<Ψ(s).\Psi(s)=\sum_{\ell=1}^{M(s)}\bigl(|V|-|C_s^\ell|\bigr),\qquad c_i(x,s_{-i})<c_i(s)\;\Longrightarrow\;\Psi(x,s_{-i})<\Psi(s).Ψ(s)=ℓ=1∑M(s)​(∣V∣−∣Csℓ​∣),ci​(x,s−i​)<ci​(s)⟹Ψ(x,s−i​)<Ψ(s).

The full-support assertion in the second sentence of Theorem 1 is outside this mission's milestone list. The existence target uses its first assertion. Theorem 3's bound on improvement-path length and the paper's stochastic, constrained, and buck-holding games are also outside this target.

What the result provides

Theorem 2 guarantees a pure strategy profile with stability across all starting distributions, including distributions concentrated at a single vertex. It strengthens the statement that each fixed distribution has some equilibrium, which could choose a different profile each time. In this deterministic model the same strategy choices serve all initial laws. The paper's proof ties that claim to a graph quantity, Ψ\PsiΨ, whose value has no μ\muμ parameter. Theorems 1–2, pp. 9–10 state the potential and equilibrium conclusions.

The research result is already proved in the paper. The work here is to give its definitions and statements precise Lean types and to establish machine-checked proofs of the limit identity, graph-change classification, potential property, and existence theorem. The drafted theorem files currently contain sorry, so their compilation checks statement well-formedness rather than proving the claims. The finite cost-game definitions and orbit-frequency statement can also support later formalizations of deterministic dynamics and potential games.

Where the proof is difficult

A finite orbit is eventually periodic, but the cost is defined using a limit of averages from time 111 through TTT. The formal development must establish that limit for every initial vertex before substituting the cycle-and-basin formula. It must then track what a one-player change does to the cycles of a functional graph. The changed edge can lengthen one cycle or remove it by sending its vertices toward a different cycle; costs also depend on how much initial mass reaches the affected basin. Merely knowing that a player's new out-neighbor is in the same basin does not show an improvement, because the new cycle may be shorter or unchanged. These are the concrete issues behind equation (6) and Theorem 1.

Formalization scope

Lean gives the general cost-game predicates their own definition module. The deterministic model represents VVV by a finite type, with the paper's loopless and nonempty out-neighborhood assumptions bundled into BPGraph. A strategy is an out-neighbor subtype, so every profile selects only legal edges. The distribution is a real vector with nonnegative coordinates summing to one. Costs and the potential are real-valued. The cost is built from the orbit's Cesàro limit in equation (3); equation (6) is a separate theorem asserting convergence and the resulting value. Cycles are finite sets of periodic points, deduplicated so that Ψ\PsiΨ has exactly one summand per cycle; basins contain the vertices whose orbits reach that cycle. Classical decidability constructs these finite sets.

The empty vertex type is permitted by the Lean representation; it has one empty strategy profile and no probability distribution. A one-vertex graph cannot satisfy both the loopless and nonempty out-neighborhood assumptions. The prior-free goal explicitly places the profile before the quantifier over distributions. Defining cost by the cycle formula, or choosing a separate equilibrium after seeing each distribution, would change the target. Proposition 1 makes nonempty strategy sets explicit, as an empty compact strategy set has no profile. The first profitable-deviation case requires that the changed edge lengthen the cycle; membership in the basin alone does not do so.

The development needs reusable results on finite function iteration, periodic points, Cesàro frequencies, finite products, and lower semicontinuous minimization. The goal and its milestones invite proofs of those statements under the recorded hypotheses. All mission items are drafted locally and remain unproved until solvers supply proofs.

Selected references

  • R. Cominetti, M. Quattropani, and M. Scarsini, The Buck-Passing Game, Mathematics of Operations Research, 2022. arXiv:1808.03206v4. The formalization cites the version 4 preprint's pages and numbering.
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Quantum Information·Captain: Goku

Tight uniform continuity bounds for quantum entropies: conditional entropy, relative entropy distance and energy constraintsResearch Paper

Motivation

We present a bouquet of continuity bounds for quantum entropies, falling broadly into two classes: First, a tight analysis of the Alicki-Fannes continuity bounds for the conditional von Neumann entropy, reaching almost the best possible form that depends only on the system dimension and the trace distance of the states. Almost the same proof can be used to derive similar continuity bounds for the relative entropy distance from a convex set of states or positive operators. As applications we give new proofs, with tighter bounds, of the asymptotic continuity of the relative entropy of entanglement, ERE_RER​, and its regularization ER∞E_R^\inftyER∞​, as well as of the entanglement of formation, EFE_FEF​. Using a novel "quantum coupling" of density operators, which may be of independent interest, we extend the latter to an asymptotic continuity bound for the regularized entanglement of formation, aka entanglement cost, EC=EF∞E_C=E_F^\inftyEC​=EF∞​. Second, analogous continuity bounds for the von Neumann entropy and conditional entropy in infinite dimensional systems under an energy constraint, most importantly systems of multiple quantum harmonic oscillators. While without an energy bound the entropy is discontinuous, it is well-known to be continuous on states of bounded energy. However, a quantitative statement to that effect seems not to have been known. Here, under some regularity assumptions on the Hamiltonian, we find that, quite intuitively, the Gibbs entropy at the given energy roughly takes the role of the Hilbert space dimension in the finite-dimensional Fannes inequality.

This mission is the statement-level formalization of Tight uniform continuity bounds for quantum entropies: conditional entropy, relative entropy distance and energy constraints (arXiv:1507.07775v6). 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 Remark 3: explicit near-tightness example for Lemma 2 (Remark 3: explicit near-tightness example for Lemma 2, 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

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

  • Lemma 2: almost tight conditional entropy continuity (paper headline): Normalized trace-class bipartite states, partial traces, extended conditional entropy, common-basis qc/cq predicates (hard)
  • Corollary 4: continuity of entanglement of formation and entanglement cost: Countable exact pure-state ensembles, entanglement of formation, and its tensor-power regularization with an infinite factor (hard)
  • Remark 6: separable infinite-dimensional extension of Proposition 5: Trace-class tensor-square states, Hilbert-Schmidt vectorization, marginals, basis transpose and root fidelity (hard)
  • Corollary 8: continuity of relative entropy of entanglement and its regularization: Infinite-factor Umegaki relative entropy, closed separable-state set, E_R and E_R-infinity (hard)
  • Proposition 14: quantum coupling with large operator norm: Arbitrary separable trace-class couplings, tensor marginals and operator norm (hard)
  • Lemma 15: energy-constrained entropy continuity by coupling: Arbitrary finite-energy trace-class states, full spectral entropy, trace distance and quadratic-form energy (hard)
  • Meta-Lemma 16: adjustable-cutoff energy-constrained entropy continuity: Arbitrary finite-energy trace-class states and their spectral entropy and trace distance (hard)
  • Meta-Lemma 17: energy-constrained conditional entropy continuity: Infinite-dimensional bipartite trace-class states with finite-A-entropy conditional extension and A-only form energy (hard)
  • Eq. (19): oscillator Gibbs entropy bound and equal-allocation maximization: A correct optimizing equality for the unequal-frequency allocation simplex (source-ambiguity)
  • Lemma 18: explicit harmonic-oscillator entropy and conditional entropy bounds: Full Fock trace-class input states, oscillator quadratic-form energy, and arbitrary-ancilla conditional entropy (hard)
  • Remark 19: large-energy sharpness of oscillator leading coefficients: Actual mixed Fock witnesses, Gibbs purification, trace distance and conditional entropy, plus large-energy comparison (hard)
  • Unnumbered consequence: uniform continuity at each fixed energy: A trace-distance state domain of arbitrary bounded-energy densities and uniform-in-B conditional entropy (hard)

Selected references

  • Tight uniform continuity bounds for quantum entropies: conditional entropy, relative entropy distance and energy constraints, arXiv:1507.07775v6, https://arxiv.org/abs/1507.07775v6
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EconomicsOperations Research·Captain: mikedeng1

A Theory of ICOs: Diversification, Agency, and Information Asymmetry: Tokens Have a Signaling Advantage over Equity Exactly for Moderate Venture Heterogeneity and for Moderate Payoff VolatilityResearch Paper

Why financing can convey venture quality

An entrepreneur who knows more about a venture than its investors can convey information through the share of the venture that she keeps. A larger retained share exposes her to more of its uncertain payoff. The cost of this signal depends on what investors buy: an equity claim receives revenue after production costs, while a token claim receives a share of gross revenue. Chod and Lyandres examine how that difference affects the ability of high- and low-quality ventures to separate in an initial coin offering. Their analysis identifies a range of venture heterogeneity and payoff volatility in which tokens support separation and equity does not. The source for this mission is their SSRN working paper, version of December 14, 2019, §4 and Proposition 6.

This result concerns a specific information problem. Investors cannot observe venture quality before buying; an entrepreneur knows her own type. If the same financing contract is used regardless of type, investors cannot identify quality from the offering. A separating outcome instead assigns different sale fractions to the two types and makes the resulting investor beliefs consistent with each type's incentives. The paper compares the feasibility of such outcomes for the two securities, under a model in which the agency effects studied in its earlier sections are set aside.

The two-type financing game

There are two venture types, high HHH and low LLL. The entrepreneur observes the type; investors observe the fraction α\alphaα offered for sale. Type iii has uncertain shock Xi=ξi2X_i=\xi_i^2Xi​=ξi2​ with a normal approximation of mean μi\mu_iμi​ and standard deviation σ\sigmaσ, where μH>μL\mu_H>\mu_LμH​>μL​. Revenue is Ri=Xi/4R_i=X_i/4Ri​=Xi​/4. The entrepreneur pays fixed production cost CCC and initial investment III. Her CARA utility at terminal wealth ω\omegaω is

uγ(ω)=γ−1−γ−1exp⁡(−γω),γ>0.u_\gamma(\omega)=\gamma^{-1}-\gamma^{-1}\exp(-\gamma\omega),\qquad\gamma>0.uγ​(ω)=γ−1−γ−1exp(−γω),γ>0.

Under a belief that the venture has type jjj, investors value the revenue using that type's distribution. An actual type iii who sells fraction α\alphaα therefore receives the cash value αEj[Rj]\alpha\mathbb E_j[R_j]αEj​[Rj​], retains fraction 1−α1-\alpha1−α of her own realized revenue, and has expected utility

Uij(α)=Ei[uγ ⁣(αEj[Rj]+(1−α)Ri−C−I)].U_{ij}(\alpha)=\mathbb E_i\left[u_\gamma\!\left(\alpha\mathbb E_j[R_j]+(1-\alpha)R_i-C-I\right)\right].Uij​(α)=Ei​[uγ​(αEj​[Rj​]+(1−α)Ri​−C−I)].

The financing method changes the smallest fraction she must sell. The equity financing threshold is αˉjE=I/(Ej[Rj]−C)\bar\alpha_j^E=I/(\mathbb E_j[R_j]-C)αˉjE​=I/(Ej​[Rj​]−C), and the token financing threshold is αˉjT=I/Ej[Rj]\bar\alpha_j^T=I/\mathbb E_j[R_j]αˉjT​=I/Ej​[Rj​]. The cost CCC appears in the equity denominator because equity buyers receive a claim after that cost. With a positive cost, the token threshold is strictly smaller.

Investors use a threshold belief: they infer HHH when α≤t\alpha\le tα≤t and LLL when α>t\alpha>tα>t. A separating equilibrium requires both types to prefer the side of the threshold assigned to them, subject to their financing constraints. The paper's conditions (23) and (24) compare the best feasible payoffs on the two sides. A least-cost separating equilibrium is a separating equilibrium that is not Pareto-dominated by another such equilibrium. The paper defines an interior share α∗\alpha^*α∗ in equation (25); Proposition 5 identifies its role as the least-cost threshold whenever separation is feasible.

Formalization targets

The central question is when tokens have a signaling advantage: a separating equilibrium exists with tokens, and none exists with equity. Proposition 6 gives two parameter windows. For fixed values of the other parameters, there are thresholds μl<μu\mu_l<\mu_uμl​<μu​ and σl<σu\sigma_l<\sigma_uσl​<σu​ such that

token signaling advantage⟺μl≤μL<μu,\text{token signaling advantage}\quad\Longleftrightarrow\quad\mu_l\le\mu_L<\mu_u,token signaling advantage⟺μl​≤μL​<μu​,

and, in a separate comparison,

token signaling advantage⟺σl≤σ<σu.\text{token signaling advantage}\quad\Longleftrightarrow\quad\sigma_l\le\sigma<\sigma_u.token signaling advantage⟺σl​≤σ<σu​.

The first window varies the low-type mean while keeping the high-type mean fixed. Increasing μL\mu_LμL​ reduces the difference between the types. The second varies payoff volatility. Both claims concern the game's equilibrium conditions, rather than only a numerical inequality between closed-form expressions.

The milestone sequence begins with the CARA-normal expected-utility formula (38) and the interior range of α∗\alpha^*α∗. It then records the low type's indifference at α∗\alpha^*α∗ and the threshold form of condition (24). Proposition 5 characterizes the equilibrium under each security. The remaining milestones compare the financing thresholds and record the monotonicity of α∗\alpha^*α∗ with respect to μL\mu_LμL​ and σ\sigmaσ. These are the paper's stated results and intermediate claims in §4 and its appendix.

What the result establishes

The theorem isolates a case in which the form of the security changes what investors can infer. A token offering can permit the high type to sell enough to finance the investment while retaining a stake that the low type does not want to imitate. Equity may require a larger sale fraction, closing that opportunity. The window statement also says the advantage is limited: when types are too different or too similar, or when volatility is outside the relevant range, tokens do not uniquely enable separation under this model.

A machine-checked development would connect an explicit probabilistic payoff model, incentive comparisons over feasible actions, the equilibrium characterization, and comparative statics in one chain. The cited paper proves these results informally; the theorem files here are open proof targets. The CARA-normal calculation and the representation of threshold equilibria are reusable in other signaling models with normally distributed payoffs.

Where the mathematical work lies

The direct comparison of financing thresholds is insufficient for the goal. Separation also depends on whether a low-quality entrepreneur would imitate a high-quality one, and whether a high-quality entrepreneur prefers to reveal her type. These conditions optimize utility over different feasible sale fractions, including a strict boundary on the low-belief side of the threshold. The paper's closed form for α∗\alpha^*α∗ expresses the point at which the low type becomes indifferent, but the full result must also establish the high type's incentive and the uniqueness of the refined equilibrium.

The comparative statics require control of two moving parts: the threshold α∗\alpha^*α∗ changes with the low-type mean and volatility, while the high-type financing thresholds remain fixed in those comparisons. The interval endpoints in Proposition 6 are existential, so their placement must reflect the feasible parameter domain and the strict or weak inequalities at each boundary.

Formalization scope

Lean represents the normal approximation for Xi=ξi2X_i=\xi_i^2Xi​=ξi2​ directly with gaussianReal of mean μi\mu_iμi​ and variance σ2\sigma^2σ2. This follows the paper's approximation even though a literal square is nonnegative and a nondegenerate normal variable is not. Revenue is Xi/4X_i/4Xi​/4. Expected utility remains a Gaussian integral; equation (38) is a theorem target, not a definition of that utility. All payoffs and thresholds are real numbers.

The parameter domain has γ>0\gamma>0γ>0, σ>0\sigma>0σ>0, μL<μH\mu_L<\mu_HμL​<μH​, C>0C>0C>0, I>0I>0I>0, and I≤μL/4−CI\le\mu_L/4-CI≤μL​/4−C. The last two substantive additions to the page's stated model are C>0C>0C>0, needed for the strict token-equity threshold comparison, and the low-type financing condition, needed for the paper's action αL=1\alpha_L=1αL​=1 to be feasible. An equilibrium threshold satisfies αˉHi≤t<1\bar\alpha_H^i\le t<1αˉHi​≤t<1. The least-cost refinement is represented by the paper's operational exclusion of Pareto-dominated separating equilibria, without claiming a general formalization of the Cho–Kreps intuitive criterion.

The high and low incentive conditions quantify only over feasible fractions. Equilibrium payoffs use real suprema on the corresponding action sets; within an equilibrium these sets are nonempty and the utility is bounded above. The goal defines signaling advantage through existence and nonexistence of separating equilibria, so it cannot be discharged by redefining the advantage as the closed-form inequality. Useful contributions include Gaussian expected-utility lemmas, optimization over the feasible intervals, equilibrium existence and uniqueness, and the real-analysis results needed for the parameter windows.

Selected references

  • Jacob Chod and Evgeny Lyandres, A Theory of ICOs: Diversification, Agency, and Information Asymmetry, SSRN working paper 3159528, version of December 14, 2019, §4 and Appendix; published in Management Science. Working paper. Published article DOI.
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Quantum Information·Captain: Goku

Bounds on entanglement distillation and secret key agreement for quantum broadcast channelsResearch Paper

Motivation

The squashed entanglement of a quantum channel is an additive function of quantum channels, which finds application as an upper bound on the rate at which secret key and entanglement can be generated when using a quantum channel a large number of times in addition to unlimited classical communication. This quantity has led to an upper bound of log⁡((1+η)/(1−η))\log((1+\eta)/(1-\eta))log((1+η)/(1−η)) on the capacity of a pure-loss bosonic channel for such a task, where η\etaη is the average fraction of photons that make it from the input to the output of the channel. The purpose of the present paper is to extend these results beyond the single-sender single-receiver setting to the more general case of a single sender and multiple receivers (a quantum broadcast channel). We employ multipartite generalizations of the squashed entanglement to constrain the rates at which secret key and entanglement can be generated between any subset of the users of such a channel, along the way developing several new properties of these measures. We apply our results to the case of a pure-loss broadcast channel with one sender and two receivers.

This mission is the statement-level formalization of Bounds on entanglement distillation and secret key agreement for quantum broadcast channels (arXiv:1503.08139v2). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.

What is formalized

1 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Thermal-entropy difference: monotonicity and finite or infinite limit (§7, paragraph containing (7.18), PDF p. 28). 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:

  • Abstract seed pinned to Theorem 12, §5: simultaneous eight-rate outer bound: Operational eight-rate broadcast achievability and computed channel-output squashed measures (hard)
  • Lemma 3: characterization by squashing a fixed purification: Unrestricted-extension and fixed-purification squashing definitions (hard)
  • Lemma 6 (Subadditivity): Both computed squashed measures on three marginals/groupings of one pure state (hard)
  • Lemma 7: monotonicity under grouping: Same-state tensor regrouping and both computed squashed measures (hard)
  • Lemma 8: reduction for a product party: Tensor-product density states and computed unrestricted-extension measures (hard)
  • Unnumbered §3.4: four cut bounds for the eight-factor ideal target, (3.62)–(3.71): Independent eight-factor GHZ/private target and its grouped measures (hard)
  • Lemma 11: resource lower bound across every nontrivial partition: Subset-indexed independent quantum-resource target and computed grouped measures (hard)
  • Theorem 13, §6: all-partition m-receiver outer bound: Subset-rate broadcast protocols and one pure witness for every partition (hard)
  • Unnumbered §7: both output-entropy bounds and finite-energy bounds, (7.11),(7.17),(7.23),(7.28): Fock broadcast dilation, environmental beamsplitter and actual conditional output entropies (hard)
  • Proposition 14: optimized photon-number independent broadcast squashed-entanglement bound: Computed Fock-channel squashed-measure suprema and boundary-aware optimization (hard)
  • Theorem 15: four explicit two-receiver bosonic rate bounds: Operational bosonic eight-rate protocols and corrected vacuum passive splitter (hard)

Selected references

  • Bounds on entanglement distillation and secret key agreement for quantum broadcast channels, arXiv:1503.08139v2, https://arxiv.org/abs/1503.08139v2
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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
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