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Round-six lemma `phiBE_runs`

Proved
NLogN.KFUU.R6Crt.phiBE_runs

by xuanji · Oct 20, 2026 · Mathlib 0df444a (Lean v4.33.1)

complexity-theoryinteger-multiplicationkappa-improvement

An auxiliary lemma of the round-six development, published as a separate node because its proof is long or shared.

The following holds (Lean statement, in the scope of module Solutions.R6CrtPhiB):

theorem NLogN.KFUU.R6Crt.phiBE_runs {pM : Fin P} (hM : MulOK I iprog pM MS) {eSw : Fin P} {sdS : Fin HS} {K : ℝ}
    (hK : SwOKτ τ I iprog eSw sdS K) (hdS : sdS ≠ 0) {Dsc : Fin HS} (hD : Dsc = 18 ∨ Dsc = 19)
    (hDd : Dsc ≠ sdS) (w h d : ℕ) (bL : ℕ → Bool) (sF μ : ℕ → ℕ) (hh : 1 ≤ h) (hd2 : 2 ≤ d)
    (hs : ∀ j < d, 1 ≤ sF j) (hst : ∀ j < d, sF j ≤ 2 ^ (h + if bL j then 1 else 0))
    (hμ : ∀ j < d, μ j < sF j)
    (s : IState HS) (f : Fin HS → List ℤ) (l : List ℤ) (hf : ∀ j, j ≠ 0 → j ≠ dP → f j = [])
    (hfd : f dP = KFM.descPhi w h d bL sF μ) (ys : List ℤ) (h0 : f 0 = ys ++ l)
    (hlen : ys.length = vol (shR d (tP d h bL))) (hb : Bnd w ys)
    (B Z Br Bb : ℕ) (hwB : zsz (w : ℤ) ≤ B) (hhB : h + 1 ≤ B) (h2B : zsz ((2 ^ h * 2 : ℕ) : ℤ) ≤ B)
    (h3B : zsz ((3 + 3 * d : ℕ) : ℤ) ≤ B) (hVB : zsz ((vol (shR d (sP d sF)) : ℕ) : ℤ) ≤ B)
    (hZ3 : 3 ≤ Z) (hZT : zsz ((vol (shR d (tP d h bL)) : ℕ) : ℤ) ≤ Z) (hwZ : zsz (w : ℤ) ≤ Z)
    (hUZ : zsz ((2 ^ h : ℕ) : ℤ) ≤ Z)
    (hVr : zsz ((vol (shR d (sP d sF)) : ℕ) : ℤ) ≤ Br) (hdr : zsz (d : ℤ) ≤ Br)
    (hVb : zsz ((vol (shR d (sP d sF)) : ℕ) : ℤ) ≤ Bb) :
    IRuns I iprog (phiBE pM eSw sdS Dsc) (encK s f)
      (encK s (Function.update f 0 (PhiInvD h d bL sF μ ys ++ l))) (cBwdE τ K w h d bL sF B Z Br Bb)

Context. CRT reversal §10: Φ⁻¹ with revE (a copy of KFUU §9c, KFUUPhiB, with revU → revE)

phiBE: read the descriptor (readD onto xS, xM), build the lists (mkL, the sizes and multipliers in forward order on oSL, oML), unpad T_r → S_r, the d backward shifts (rotsBU), pad S_r → T_r, reverse back (revU), unpad T_k → S_k, clear. phiBE_runs: it computes KFU.PhiInvD.

Formalization Note. Part of the Lean formalization of the round-six κ-improvement (integer-multiplication-kappa campaign, target IntMul.Kappa.jain_round6_framework). The statement is copied verbatim from the Lean development; the platform node carries the same declaration name. Definitions it mentions live in the IntMul_Kappa_R6_Defs* bundles (on top of the published κ bundles IntMul_Kappa_K_Defs*).

Preamble
-- Round-six κ development (integer-multiplication-kappa), generated by skeleton subtraction.

import Definitions.Def_IntMul_Kappa_R6_Defs14

set_option autoImplicit false
set_option relaxedAutoImplicit false
set_option maxHeartbeats 1000000

open NLogN NLogN.KFUU NLogN.KFUU.R6Crt
open IntMul NLogN.KIL NLogN.KFB NLogN.KFC NLogN.KFT NLogN.KFU AModel AModelL12 NLogN.KFUU
variable {P : ℕ} {I : List Sym} {iprog : Fin P → IStmt HS P} {τ : ℝ}
Formal statement
theorem NLogN.KFUU.R6Crt.phiBE_runs {pM : Fin P} (hM : MulOK I iprog pM MS) {eSw : Fin P} {sdS : Fin HS} {K : ℝ}
    (hK : SwOKτ τ I iprog eSw sdS K) (hdS : sdS ≠ 0) {Dsc : Fin HS} (hD : Dsc = 18 ∨ Dsc = 19)
    (hDd : Dsc ≠ sdS) (w h d : ℕ) (bL : ℕ → Bool) (sF μ : ℕ → ℕ) (hh : 1 ≤ h) (hd2 : 2 ≤ d)
    (hs : ∀ j < d, 1 ≤ sF j) (hst : ∀ j < d, sF j ≤ 2 ^ (h + if bL j then 1 else 0))
    (hμ : ∀ j < d, μ j < sF j)
    (s : IState HS) (f : Fin HS → List ℤ) (l : List ℤ) (hf : ∀ j, j ≠ 0 → j ≠ dP → f j = [])
    (hfd : f dP = KFM.descPhi w h d bL sF μ) (ys : List ℤ) (h0 : f 0 = ys ++ l)
    (hlen : ys.length = vol (shR d (tP d h bL))) (hb : Bnd w ys)
    (B Z Br Bb : ℕ) (hwB : zsz (w : ℤ) ≤ B) (hhB : h + 1 ≤ B) (h2B : zsz ((2 ^ h * 2 : ℕ) : ℤ) ≤ B)
    (h3B : zsz ((3 + 3 * d : ℕ) : ℤ) ≤ B) (hVB : zsz ((vol (shR d (sP d sF)) : ℕ) : ℤ) ≤ B)
    (hZ3 : 3 ≤ Z) (hZT : zsz ((vol (shR d (tP d h bL)) : ℕ) : ℤ) ≤ Z) (hwZ : zsz (w : ℤ) ≤ Z)
    (hUZ : zsz ((2 ^ h : ℕ) : ℤ) ≤ Z)
    (hVr : zsz ((vol (shR d (sP d sF)) : ℕ) : ℤ) ≤ Br) (hdr : zsz (d : ℤ) ≤ Br)
    (hVb : zsz ((vol (shR d (sP d sF)) : ℕ) : ℤ) ≤ Bb) :
    IRuns I iprog (phiBE pM eSw sdS Dsc) (encK s f)
      (encK s (Function.update f 0 (PhiInvD h d bL sF μ ys ++ l))) (cBwdE τ K w h d bL sF B Z Br Bb) := by sorry
Source
S. Jain, round-six networks for the integer-multiplication κ-improvement campaign (https://github.com/Swapnil-jain/integer-mult-kappa, commit 5868dc7) and D. Colkitt, integer-mult-bounds (https://github.com/CrocSwap/integer-mult-bounds); target `IntMul.Kappa.jain_round6_framework`. Lean declaration `NLogN.KFUU.R6Crt.phiBE_runs`, Solutions/R6CrtPhiB.lean (lines 51–405) of the round-six development.

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