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Tableau formula correctness

Proved
PvsNP.tableauCNF_correct

by alexcarter · Sep 13, 2026 · Mathlib 0df444a (Lean v4.33.1)

complexity-theoryformalizationp-vs-np

The combined formula is satisfiable exactly when a tableau satisfies the explicitly defined cell, initial, boundary, accepting and local-window constraints.

Status: Known mathematics / implementation obligation awaiting formal proof.

Formal statement
import Definitions.Def_PvsNPFrontier

namespace PvsNP
theorem tableauCNF_correct (S : TableauSpec) :
    Satisfiable (tableauCNF S) ↔ ∃ T, ValidTableau S T := by sorry
end PvsNP
Source
Sipser, Introduction to the Theory of Computation, second edition (2006), Theorem 7.37 and its proof pp. 276–281, Figures 7.38–7.40, Claim 7.41; https://users.math.cas.cz/~jerabek/teaching/mathlog/sipser-book.pdf; Cook (1971), https://www.cs.toronto.edu/~sacook/homepage/1971.pdf. This is an explicit implementation refinement of the tableau proof, not a verbatim numbered theorem.
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What the Lean code literally says, in plain math · gpt-6-astra

For every specification SSS, there exists a Boolean assignment τ:N→B\tau:\mathbb N\to Bτ:N→B making every clause of the full tableau formula true if and only if there exists a total natural-valued two-argument function TTT satisfying the validity condition described here. Neither side additionally assumes the stricter specification predicate; all specifications, including those with zero fields, missing lists, and empty accepting lists, are quantified over. Here S=(s,i,r,I,A,H)S=(s,i,r,I,A,H)S=(s,i,r,I,A,H) has s,i,r∈Ns,i,r\in\mathbb Ns,i,r∈N, a list III of lists of natural numbers, a list AAA of natural numbers, and a list HHH of lists of natural numbers, with no validity restrictions on these fields. Put W=i+2≥2W=i+2\ge2W=i+2≥2, Q=r+1≥1Q=r+1\ge1Q=r+1≥1, and v(t,c,a)=(tW+c)Q+av(t,c,a)=(tW+c)Q+av(t,c,a)=(tW+c)Q+a. The list IcI_cIc​ is the zero-based cccth list of III, or the empty list when that entry is missing. The full tableau formula is the concatenation, in order, of the cell, initial, boundary, accepting, and transition formulas described here. The cell formula consists, in increasing t=0,…,st=0,\ldots,st=0,…,s and then increasing c=0,…,W−1c=0,\ldots,W-1c=0,…,W−1, of the clause of all positive literals (true,v(t,c,a))(\mathrm{true},v(t,c,a))(true,v(t,c,a)) for a=0,…,Q−1a=0,\ldots,Q-1a=0,…,Q−1, followed by every two-literal clause [(false,v(t,c,a)),(false,v(t,c,b))][(\mathrm{false},v(t,c,a)),(\mathrm{false},v(t,c,b))][(false,v(t,c,a)),(false,v(t,c,b))] with 0≤a<b<Q0\le a<b<Q0≤a<b<Q, ordered first by aaa and then by bbb. The initial formula has, in increasing c<Wc<Wc<W and then increasing a<Qa<Qa<Q, the negative unit clause [(false,v(0,c,a))][(\mathrm{false},v(0,c,a))][(false,v(0,c,a))] exactly when a∉Ica\notin I_ca∈/Ic​. The boundary formula has, for each t=0,…,st=0,\ldots,st=0,…,s in order, the two positive unit clauses at v(t,0,0)v(t,0,0)v(t,0,0) and v(t,i+1,0)v(t,i+1,0)v(t,i+1,0), in that order. The accepting formula is a list containing one clause; its literals are (true,v(s,c,a))(\mathrm{true},v(s,c,a))(true,v(s,c,a)) for every 0≤c<W0\le c<W0≤c<W and 0≤a<Q0\le a<Q0≤a<Q with a∈Aa\in Aa∈A, ordered first by ccc and then by aaa. If no such aaa exists, this is an empty clause rather than an empty formula. The transition formula ranges in increasing order over 0≤t<s0\le t<s0≤t<s, 0≤c<i0\le c<i0≤c<i, and lexicographically over all six-tuples u∈{0,…,Q−1}6u\in\{0,\ldots,Q-1\}^6u∈{0,…,Q−1}6 absent from the list HHH. For each such tuple it has the clause of the six negative literals at positions (t,c),(t,c+1),(t,c+2),(t+1,c),(t+1,c+1),(t+1,c+2)(t,c),(t,c+1),(t,c+2),(t+1,c),(t+1,c+1),(t+1,c+2)(t,c),(t,c+1),(t,c+2),(t+1,c),(t+1,c+1),(t+1,c+2) with symbol indices given by the corresponding entries of uuu, in that order. If s=0s=0s=0 or i=0i=0i=0, the transition formula is empty. The validity condition for T:N×N→NT:\mathbb N\times\mathbb N\to\mathbb NT:N×N→N is the conjunction of: ∀t≤s, ∀c<W, T(t,c)<Q\forall t\le s,\ \forall c<W,\ T(t,c)<Q∀t≤s, ∀c<W, T(t,c)<Q; ∀c<W, T(0,c)∈Ic\forall c<W,\ T(0,c)\in I_c∀c<W, T(0,c)∈Ic​; ∀t≤s, T(t,0)=0∧T(t,i+1)=0\forall t\le s,\ T(t,0)=0\land T(t,i+1)=0∀t≤s, T(t,0)=0∧T(t,i+1)=0; ∃c<W, T(s,c)∈A\exists c<W,\ T(s,c)\in A∃c<W, T(s,c)∈A; and ∀t<s, ∀c<i, [T(t,c),T(t,c+1),T(t,c+2),T(t+1,c),T(t+1,c+1),T(t+1,c+2)]∈H\forall t<s,\ \forall c<i,\ [T(t,c),T(t,c+1),T(t,c+2),T(t+1,c),T(t+1,c+1),T(t+1,c+2)]\in H∀t<s, ∀c<i, [T(t,c),T(t,c+1),T(t,c+2),T(t+1,c),T(t+1,c+1),T(t+1,c+2)]∈H. Values outside the rectangle are unrestricted; the last condition is vacuous for s=0s=0s=0 or i=0i=0i=0, and a missing required IcI_cIc​ or an empty AAA makes the condition unsatisfiable. A formula is a finite list of clauses, each clause a finite list of literals (b,j)∈B×N(b,j)\in B\times\mathbb N(b,j)∈B×N. Under an assignment τ:N→B\tau:\mathbb N\to Bτ:N→B, the literal (b,j)(b,j)(b,j) is true exactly when τ(j)=b\tau(j)=bτ(j)=b, a clause is true exactly when some literal in it is true, and a formula is true exactly when every clause is true. Thus an empty clause is false and an empty formula is true. Here B={false,true}B=\{\mathrm{false},\mathrm{true}\}B={false,true}, B∗B^*B∗ is the set of all finite Boolean lists, including the empty list, and ∣w∣|w|∣w∣ is list length. The supplied body is admitted with sorry; no proof of this assertion is supplied there.

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