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Polynomial-time checker-to-CNF compilation

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PvsNP.checker_tableau_compilation

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

complexity-theoryformalizationp-vs-np

For every polynomial-time checker and witness exponent, construct polynomial-size, fixed-alphabet, well-formed tableaux with polynomial-time CNF output and acceptance exactly equivalent to existence of a bounded accepted certificate.

Status: Known mathematics / implementation obligation awaiting formal proof.

Formal statement
import Definitions.Def_PvsNPFrontier

namespace PvsNP
theorem checker_tableau_compilation (R : Str × Str → Bool) (k : ℕ)
    (hR : PolyTimeChecker R) :
    ∃ spec : Str → TableauSpec,
      PolyTimeComputable (fun w => encodeCNF (tableauCNF (spec w))) ∧
      (∃ p : Polynomial ℕ, ∀ w, (spec w).steps + (spec w).interior ≤ p.eval w.length) ∧
      (∃ a : ℕ, ∀ w, (spec w).symbols = a) ∧
      (∀ w, MachineTableauSpec (spec w)) ∧
      (∀ w, (∃ T, ValidTableau (spec w) T) ↔
        ∃ y : Str, y.length ≤ w.length ^ k ∧ R (w,y) = true) := 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 checker R:B∗×B∗→BR:B^*\times B^*\to BR:B∗×B∗→B, every k∈Nk\in\mathbb Nk∈N, and the hypothesis C(R)C(R)C(R), there exists a function spec⁡:B∗→S\operatorname{spec}:B^*\to\mathcal Sspec:B∗→S, where S\mathcal SS consists of the six-field specifications described here, satisfying all five conditions: the map w↦E(Fspec⁡(w))w\mapsto E(F_{\operatorname{spec}(w)})w↦E(Fspec(w)​) satisfies FFF; there exists p∈N[X]p\in\mathbb N[X]p∈N[X] such that ∀w, sspec⁡(w)+ispec⁡(w)≤p(∣w∣)\forall w,\ s_{\operatorname{spec}(w)}+i_{\operatorname{spec}(w)}\le p(|w|)∀w, sspec(w)​+ispec(w)​≤p(∣w∣); there exists a single a∈Na\in\mathbb Na∈N such that ∀w, rspec⁡(w)=a\forall w,\ r_{\operatorname{spec}(w)}=a∀w, rspec(w)​=a; every spec⁡(w)\operatorname{spec}(w)spec(w) satisfies the additional specification condition; and ∀w\forall w∀w, existence of a total function TTT satisfying the validity condition for spec⁡(w)\operatorname{spec}(w)spec(w) is equivalent to ∃y∈B∗, ∣y∣≤∣w∣k∧R(w,y)=true\exists y\in B^*,\ |y|\le|w|^k\land R(w,y)=\mathrm{true}∃y∈B∗, ∣y∣≤∣w∣k∧R(w,y)=true. Here FSF_SFS​ is the full tableau formula described here; the selected specification function, polynomials, and fixed symbol count may depend on R,kR,kR,k and its hypothesis, while the two displayed global bounds apply to all words. This includes the empty word, with 00=10^0=100=1 and 0k=00^k=00k=0 for k>0k>0k>0. 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. Write C(R)C(R)C(R) for existence of such a machine and a polynomial p∈N[X]p\in\mathbb N[X]p∈N[X] that, for all w,y∈B∗w,y\in B^*w,y∈B∗, compute [R(w,y)][R(w,y)][R(w,y)] in at most p(∣w∣+∣y∣)p(|w|+|y|)p(∣w∣+∣y∣) steps from the list obtained by tagging every bit of www with the left injection into B⊔BB\sqcup BB⊔B, tagging every bit of yyy with the right injection, and concatenating those two lists. Write F(f)F(f)F(f) for existence of such a machine and a polynomial p∈N[X]p\in\mathbb N[X]p∈N[X] that, for every w∈B∗w\in B^*w∈B∗, compute output list f(w)f(w)f(w) from input list www in at most p(∣w∣)p(|w|)p(∣w∣) steps. Different existential computation witnesses may use different machines and polynomials. A machine in these assertions is a Mathlib TM2 stack machine with finitely many stack indices, instruction labels, and control states, a finite input-stack alphabet, designated input and output stacks, a program, and initial label and control state; its other stack alphabets need not be finite. Input and output alphabet bijections transport the specified encoded lists to the corresponding stack alphabets. Computation starts with only the input stack populated, and reaches a halted configuration with the specified output on the output stack, all other stacks empty, and the control state reset to its initial value. Time counts executions of whole TM2 statements, each of which may contain several stack operations. 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 additional specification condition is exactly s>0s>0s>0, i>0i>0i>0, 0∉A0\notin A0∈/A, ∣I∣=W|I|=W∣I∣=W, every entry of every list in III is below QQQ, every entry of AAA is below QQQ, and every list in HHH has length exactly six and every one of its entries is below QQQ. It imposes no nonemptiness condition on an individual list in III, on AAA, or on HHH, and allows r=0r=0r=0; in that case Q=1Q=1Q=1 and the accepting list must be empty. 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. 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. 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. The supplied body is admitted with sorry; no proof of this assertion is supplied there.

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