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Equation (5.2) and Lemma 5.2: same-marginal entropy correction

Proved
mme_stothers_lemma52_same_marginal

by marwahaha · Aug 29, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

algebraic-complexitycoppersmith-winogradlaser-methodmatrix-multiplication

Let Q:R10→R9Q:\mathbb R^{10}\to\mathbb R^9Q:R10→R9 be the marginal map of Equation (5.2). First, its kernel is exactly the span of

(0,0,1,0,−2,−2,0,2,0,−2),(0,0,0,1,−2,0,−1,1,2,−2).(0,0,1,0,-2,-2,0,2,0,-2),\qquad (0,0,0,1,-2,0,-1,1,2,-2).(0,0,1,0,−2,−2,0,2,0,−2),(0,0,0,1,−2,0,−1,1,2,−2).

Second, let a,b∈R10a,b\in\mathbb R^{10}a,b∈R10. Assume a∈Za\in Za∈Z, b∈Nb\in\mathcal Nb∈N, every coordinate of bbb is strictly positive, and a−ba-ba−b lies in that two-dimensional kernel. Then

∏i=110binibi≤∏i=110ainiai.\prod_{i=1}^{10} b_i^{n_i b_i} \le \prod_{i=1}^{10} a_i^{n_i a_i}.i=1∏10​bini​bi​​≤i=1∏10​aini​ai​​.

The stationary set N\mathcal NN is the subset of ZZZ satisfying b3b82=b5b6b10b_3b_8^2=b_5b_6b_{10}b3​b82​=b5​b6​b10​ and b4b8b9=b5b7b10b_4b_8b_9=b_5b_7b_{10}b4​b8​b9​=b5​b7​b10​. These are the equations derived in Stothers's thesis and from the displayed kernel; they correct the inconsistent equations printed in the journal.

Preamble
import Definitions.Def_mme_stothers_fourth_data

open MME BigOperators

set_option autoImplicit false
Formal statement
theorem mme_stothers_lemma52_same_marginal :
    (∀ x : Fin 10 → Real,
      (∀ j : Fin 9, MME.StothersFourth.Q x j = 0) ↔
        MME.StothersFourth.InY x) ∧
    (∀ a b : Fin 10 → Real,
      MME.StothersFourth.InZ a →
      MME.StothersFourth.InN b →
      (∀ i : Fin 10, 0 < b i) →
      MME.StothersFourth.InY (fun i => a i - b i) →
      MME.StothersFourth.entropyProduct b ≤
        MME.StothersFourth.entropyProduct a) := by
  sorry
Source
Davie and Stothers (2013), Equation (5.2) and Lemma 5.2, printed pp. 367-368, https://www.maths.ed.ac.uk/~sandy/a11164.pdf; corrected stationary equations from Stothers thesis (2010), Chapter 4.2, printed pp. 78-79.
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mme_stothers_lemma52_same_marginal

The theorem is the conjunction of two assertions over real 101010-coordinate vectors and has no field, tensor, or τ\tauτ parameter. First, for every x=(x0,…,x9)∈R10x=(x_0,\ldots,x_9)\in\mathbb R^{10}x=(x0​,…,x9​)∈R10, the following nine equations hold simultaneously, 2x0+2x1+2x2+2x3+x4=02x_0+2x_1+2x_2+2x_3+x_4=02x0​+2x1​+2x2​+2x3​+x4​=0, 2x1+2x5+2x6+2x7=02x_1+2x_5+2x_6+2x_7=02x1​+2x5​+2x6​+2x7​=0, 2x2+2x6+2x8+x9=02x_2+2x_6+2x_8+x_9=02x2​+2x6​+2x8​+x9​=0, 2x3+2x7+2x9=02x_3+2x_7+2x_9=02x3​+2x7​+2x9​=0, 2x4+2x7+x8=02x_4+2x_7+x_8=02x4​+2x7​+x8​=0, 2x3+2x6=02x_3+2x_6=02x3​+2x6​=0, 2x2+x5=02x_2+x_5=02x2​+x5​=0, 2x1=02x_1=02x1​=0, and x0=0x_0=0x0​=0, if and only if there exist real numbers s,ts,ts,t such that x=(0,0,s,t,−2s−2t,−2s,−t,2s+t,2t,−2s−2t)x=(0,0,s,t,-2s-2t,-2s,-t,2s+t,2t,-2s-2t)x=(0,0,s,t,−2s−2t,−2s,−t,2s+t,2t,−2s−2t); both directions of the equivalence are asserted, while uniqueness of s,ts,ts,t is not part of the stated right-hand side. Second, for every pair a=(a0,…,a9)a=(a_0,\ldots,a_9)a=(a0​,…,a9​) and b=(b0,…,b9)b=(b_0,\ldots,b_9)b=(b0​,…,b9​) of real vectors, if (i) every ai≥0a_i\ge0ai​≥0 and a0+2a1+2a2+2a3+a4+a5+2a6+2a7+a8+a9=1a_0+2a_1+2a_2+2a_3+a_4+a_5+2a_6+2a_7+a_8+a_9=1a0​+2a1​+2a2​+2a3​+a4​+a5​+2a6​+2a7​+a8​+a9​=1; (ii) every bi≥0b_i\ge0bi​≥0, b0+2b1+2b2+2b3+b4+b5+2b6+2b7+b8+b9=1b_0+2b_1+2b_2+2b_3+b_4+b_5+2b_6+2b_7+b_8+b_9=1b0​+2b1​+2b2​+2b3​+b4​+b5​+2b6​+2b7​+b8​+b9​=1, b2b72=b4b5b9b_2b_7^2=b_4b_5b_9b2​b72​=b4​b5​b9​, and b3b7b8=b4b6b9b_3b_7b_8=b_4b_6b_9b3​b7​b8​=b4​b6​b9​; (iii) in addition, every coordinate of bbb is strictly positive; and (iv) there exist real s,ts,ts,t such that a−b=(0,0,s,t,−2s−2t,−2s,−t,2s+t,2t,−2s−2t)a-b=(0,0,s,t,-2s-2t,-2s,-t,2s+t,2t,-2s-2t)a−b=(0,0,s,t,−2s−2t,−2s,−t,2s+t,2t,−2s−2t), then F(b)≤F(a)F(b)\le F(a)F(b)≤F(a), where, writing R(x,r)=Real.rpow⁡(x,r)R(x,r)=\operatorname{Real.rpow}(x,r)R(x,r)=Real.rpow(x,r), F(x)=R(x0,x0)R(x1,2x1)R(x2,2x2)R(x3,2x3)R(x4,x4)R(x5,x5)R(x6,2x6)R(x7,2x7)R(x8,x8)R(x9,x9)F(x)=R(x_0,x_0)R(x_1,2x_1)R(x_2,2x_2)R(x_3,2x_3)R(x_4,x_4)R(x_5,x_5)R(x_6,2x_6)R(x_7,2x_7)R(x_8,x_8)R(x_9,x_9)F(x)=R(x0​,x0​)R(x1​,2x1​)R(x2​,2x2​)R(x3​,2x3​)R(x4​,x4​)R(x5​,x5​)R(x6​,2x6​)R(x7​,2x7​)R(x8​,x8​)R(x9​,x9​). The conclusion is non-strict; aaa is required only to be nonnegative, not strictly positive and not to satisfy the two polynomial equations, so zero coordinates of aaa are included and contribute R(0,0)=1R(0,0)=1R(0,0)=1 under the total real-power operation; strict positivity is imposed only on bbb, in addition to all of the nonnegativity, normalization, and polynomial conditions already contained in its second premise. Because the premises form an implication chain, the second assertion imposes no comparison when any one of them fails.

Human review
  • Endorsed by Shuze Chen · Aug 30, 2026

  • Endorsed by marwahaha · Aug 30, 2026

    Confirmed by the mission captain (proposal self-audit).

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