Provedalphabaguettebaguette-zv2
Attention-sublayer increment ≤ (row ℓ₁ norm of W_o) × (value bound), for the existing architecture
For all , , , and , if , and , then
What the notation means · or point at any symbol
- NNatural numbers
- The natural numbers 0, 1, 2, …. In Lean they start at 0. (
ℕ) - x ∈ TVariables
- T, d range over natural numbers: the statement must hold for every choice. (
(T d : ℕ)) - Fin
- Fin: a definition from the library, not special notation. Its name is its meaning; open it in Lean to see how it is defined. (
Fin) - f(x)Function application
- Fin applied to T. Lean writes f x; papers write f(x). (
Fin T) - ⟹Implies
- If Fin(T), then ℝ. (Between types, A → B is the type of functions from A to B.) (
Fin T → ℝ) - ∀For all
- The statement after the comma holds for every j. (
∀ j, 0 ≤ w j) - ∑Summation
- Add up w(j) for every j. (
∑ j, w j) - =Equality
- ∑ j, w(j) and 1 are the same. (
∑ j, w j = 1) - ≤At most
- 0 is less than or equal to w(j). (
0 ≤ w j) - |x|Absolute value
- The size of V(j, k) without its sign. (
|V j k|) - RReal numbers
- The real numbers: every point on the number line. (
ℝ) - ·Multiplication
- w(j) times V(j, k). (
w j * V j k)
theorem bz2-attention-increment-bound {T d : ℕ} (w : Fin T → ℝ) (hw : ∀ j, 0 ≤ w j) (hsum : ∑ j, w j = 1) (V : Fin T → Fin d → ℝ) (Wo : Fin d → ℝ) (M : ℝ) (hV : ∀ j k, |V j k| ≤ M) :
|∑ k, Wo k * ∑ j, w j * V j k| ≤ (∑ k, |Wo k|) * MComposes the convex-combination and row-sum bounds: with softmax weights and |V| ≤ M, each output coordinate of attention followed by W_o is ≤ (Σ_k|W_o,k|)·M. Here M ≤ (row ℓ₁ norm of W_v)·√n by the RMSNorm coordinate bound. A runtime residual certificate for Baguette as it is, computable from weight row sums in the optimizer, with no architecture change. Part of 'Baguette-Z v2' (revision after the hostile review).
How it was proved
- Proved
- 3 October 2026
- By
- Ajax, with the agent “Baguette math & proofs (Claude Code, 2026-10-03)”
- Checked by
- Lean's kernel (Lean 4.33.1, with Mathlib); the proof is signed and replays offline
- Axioms
- Classical.choice, Quot.sound, propext
- Proof
- 23 lines of Lean
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