§6.1 / Lemma 16 on the paper's layout

§6.1 / Lemma 16 on the paper's layout. Running the rounds h = ℓ-1, …, 0 (layer H0^{⊗} on the selected bits paperSel h, then J_E) on the records in layout L returns, at every address v, the normalized transform (F^- z)(rev(coord v)): the procedure implements B F^-.

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

theorem GlueLayout.synth_forward_paper (hK : 0 < K) (hℓ : 1 ≤ ℓ) (hy : y ^ (2 ^ ℓ) = -1) {xs : List R}
    (hlen : xs.length = vol (binSh (tgtL D ℓ K long).length))
    {v : List ℕ} (hv : Valid (binSh (tgtL D ℓ K long).length) v) :
    (procL y (paperLayout D ℓ K long hK hℓ) ℓ (partAxes (al D ℓ long))
      (paperSel D ℓ K long hK hℓ) ℓ xs).getD (encode (binSh (tgtL D ℓ K long).length) v) 0 =
      Fm y ℓ (al D ℓ long) (fn (paperLayout D ℓ K long hK hℓ) xs)
        (revV (al D ℓ long) ((paperLayout D ℓ K long hK hℓ).coord v))

Context. The lemma belongs to the part Glue 2a: the paper's layout as a CoordLayout, its selected bits, and the bridge to layerSel.

Formalization Note. This lemma belongs to the Lean formalization (integer-multiplication-kappa campaign) of the OpenAI preprint Integer multiplication below $n\log n$: the array model of tape data (mixed-radix arrays and pull maps), the interchange networks of §3–4 (Propositions 7, 8, 11, Lemmas 9–12), the butterfly layers of §5 (Lemma 13, Proposition 14), the synthesis of §6–7 (Lemma 16, Proposition 18), the resampling and parameter choices of §8–9, and the final glue IntMul.OpenAI.Glue.kappaBound_of_machine, which derives the platform bound KappaBound (1/2^182) (from Def_IntMul_MultitapeModel) for any correct multitape machine meeting the paper's time recurrence. All names refer to the definition bundles IntMul_Kappa_K_Defs1–IntMul_Kappa_K_Defs9.