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Lemma 13 for the fixed register-driven code `l13U q` (round six, `l13U_body`)

Proved
NLogN.KFX.l13U_body

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

complexity-theoryinteger-multiplicationkappa-improvement

Lemma 13 for the fixed register-driven code l13U q (Lem13Body with the parameters in the master registers σMR).

The following holds (Lean statement, in the scope of module Solutions.KFX4Core):

theorem NLogN.KFX.l13U_body :
    ∃ (q : ℕ) (Kc : ℝ), 0 < Kc ∧
    ∀ {I : List Sym} (N0 N1 N2 N3 K f ρ R w : ℕ) (px py : Fin 3), px ≠ py → 6 ≤ K → ρ < K →
      1 ≤ f → 1 ≤ N0 → 1 ≤ N1 → 1 ≤ N2 → 1 ≤ N3 → 1 ≤ R →
      ∀ (t : IState HS) (zs : List GI) (R0 : List Item),
      Agree (σMR N0 N1 N2 N3 K f ρ R w px py) t →
      t.G 0 = ints (gflat zs) ++ R0 → zs.length = vol (rect N0 N1 N2 N3 (f * K)) * R → GB w zs →
      ∃ c, IRuns I l12prog (l13U q) t
          (t.upd 0 (ints (gflat (permRecs (rect N0 N1 N2 N3 (f * K))
            (rowAddAddr K ρ f px py) R zs)) ++ R0)) c ∧
        (c : ℝ) ≤ Kc * ((zs.length : ℝ) * (w + 1) * (((f * K : ℕ) : ℝ) ^ (1 - (2 : ℝ)⁻¹ ^ 50) + 1) +
          (vol (rect N0 N1 N2 N3 (f * K)) : ℝ) * ((zsz (2 * zs.length * (w + 1) : ℤ) : ℝ) + 1) ^ 3 +
          min 1 (80 * ((f : ℝ) - 1) * 2⁻¹ ^ K) * (vol (rect N0 N1 N2 N3 (f * K)) : ℝ) *
            ((zsz (2 * zs.length * (w + 1) : ℤ) : ℝ) + 1) * ((R : ℝ) * (w + 1) +
              (zsz (2 * zs.length * (w + 1) : ℤ) : ℝ) + 1))

Context. KFX §4: the register-driven Lemma 13 core

The fixed code l13U q is KFL.l13code with every size-dependent literal read from the master registers (MReg): w, 2·M·R on 1, 6 (for toBitsU/fromBitsU), the swap flags on 11, 12, and Q = 2^{fK}, B = R·2(w+1), 2^ρ, gx, N0, N1, N2, N3, A = zsz V, 2^K on 13, 15, 16, 17, 18, 19, 46, 47, 48, 49, f, K on 36, 37. The slot swaps preL px py are realized by two optional swaps (optA: swap 0 or 2 by the flag on 11, optB: swap 1 by the flag on 12). l13U_runs is KFL.l13_runs for this code.

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_K_Defs33
import Definitions.Def_IntMul_Kappa_R6_Defs1
import Mathlib
import Definitions.Def_IntMul_HvdH_M_Defs8
import Definitions.Def_IntMul_MultitapeModel

set_option autoImplicit false
set_option relaxedAutoImplicit false
set_option maxHeartbeats 1000000

open NLogN NLogN.KFX
open IntMul NLogN.RS NLogN.KIL NLogN.KFD NLogN.KFE NLogN.KFB NLogN.KFL NLogN.KFW NLogN.KFH AModel Butterfly
Formal statement
theorem NLogN.KFX.l13U_body :
    ∃ (q : ℕ) (Kc : ℝ), 0 < Kc ∧
    ∀ {I : List Sym} (N0 N1 N2 N3 K f ρ R w : ℕ) (px py : Fin 3), px ≠ py → 6 ≤ K → ρ < K →
      1 ≤ f → 1 ≤ N0 → 1 ≤ N1 → 1 ≤ N2 → 1 ≤ N3 → 1 ≤ R →
      ∀ (t : IState HS) (zs : List GI) (R0 : List Item),
      Agree (σMR N0 N1 N2 N3 K f ρ R w px py) t →
      t.G 0 = ints (gflat zs) ++ R0 → zs.length = vol (rect N0 N1 N2 N3 (f * K)) * R → GB w zs →
      ∃ c, IRuns I l12prog (l13U q) t
          (t.upd 0 (ints (gflat (permRecs (rect N0 N1 N2 N3 (f * K))
            (rowAddAddr K ρ f px py) R zs)) ++ R0)) c ∧
        (c : ℝ) ≤ Kc * ((zs.length : ℝ) * (w + 1) * (((f * K : ℕ) : ℝ) ^ (1 - (2 : ℝ)⁻¹ ^ 50) + 1) +
          (vol (rect N0 N1 N2 N3 (f * K)) : ℝ) * ((zsz (2 * zs.length * (w + 1) : ℤ) : ℝ) + 1) ^ 3 +
          min 1 (80 * ((f : ℝ) - 1) * 2⁻¹ ^ K) * (vol (rect N0 N1 N2 N3 (f * K)) : ℝ) *
            ((zsz (2 * zs.length * (w + 1) : ℤ) : ℝ) + 1) * ((R : ℝ) * (w + 1) +
              (zsz (2 * zs.length * (w + 1) : ℤ) : ℝ) + 1)) := 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.KFX.l13U_body`, Solutions/KFX4Core.lean (lines 986–1057) of the round-six development.

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