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The intermediate tableau encoding is injective

Proved
PvsNP.encodeTableauSpec_injective

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

complexity-theoryformalizationp-vs-np

Different six-field tableau specifications have different canonical encodings.

Status: Known mathematics / implementation obligation awaiting formal proof.

Formal statement
import Definitions.Def_PvsNPFrontier

namespace PvsNP
theorem encodeTableauSpec_injective : Function.Injective encodeTableauSpec := 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 two specifications S1,S2S_1,S_2S1​,S2​, if J(S1)=J(S2)J(S_1)=J(S_2)J(S1​)=J(S2​) as Boolean words, then S1=S2S_1=S_2S1​=S2​ as structures, meaning that all six corresponding fields agree exactly, including list order and repetitions. This assertion covers every specification, without the stricter specification predicate or any validity condition. 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 specification encoding J(S)J(S)J(S) is E(GS)E(G_S)E(GS​), where GSG_SGS​ is the following clause list: first a clause of sss copies of (true,0)(\mathrm{true},0)(true,0), then a clause of iii copies, then a clause of rrr copies, then a clause of ∣I∣|I|∣I∣ copies; next, for each list xxx in III in order, the clause [(true,a):a runs through x][(\mathrm{true},a):a\text{ runs through }x][(true,a):a runs through x]; next one clause formed in the same way from AAA; finally one such clause for each list in HHH in order. These are raw formula encodings: no satisfiability condition is part of JJJ. Empty lists and zero replication counts give empty clauses, which still have their clause delimiters. Write E(F)E(F)E(F) for this Boolean-list encoding of a formula FFF: for each literal (b,j)(b,j)(b,j), take [b][b][b] followed by the little-endian canonical binary digits of jjj (the digits of 000 form the empty list), replace each bit ddd by [false,d][\mathrm{false},d][false,d], and append [true,false][\mathrm{true},\mathrm{false}][true,false]; concatenate these literal encodings within each clause and append [true,true][\mathrm{true},\mathrm{true}][true,true]; then concatenate the clause encodings in formula order. In particular E([])=[]E([])=[]E([])=[]. 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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