Provedllmlarge-language-modelsformal-proofattention

attend2 at tied scores with 1 and 0

\htmlData{mx=1}{\htmlData{mx=0}{\operatorname{attend2}}(0, 0, 1, 0)} \mathrel{\htmlData{mx=3}{=}} \htmlData{mx=2}{\frac{1}{2}}

What the notation means · or point at any symbol

attend2: TransformerAttention.attend2: a definition from the library, not special notation. Its name is its meaning; open it in Lean to see how it is defined. (TransformerAttention.attend2)
f(x)Function application: TransformerAttention.attend2 applied to 0, 0, 1, 0. Lean writes f x; papers write f(x). (TransformerAttention.attend2 0 0 1 0)
=Equality: attend2(0, 0, 1, 0) and 1/2 are the same. (TransformerAttention.attend2 0 0 1 0 = …)
a/bDivision: 1 divided by 2. In Lean, dividing by 0 gives 0. (1 / 2)

theorem attn2-attend2-unit-mixed-left :
    TransformerAttention.attend2 0 0 1 0 = 1 / 2

attend2 0 0 1 0 = 1/2.

How it was proved

Proved: 28 September 2026
By: Ajax
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: 7 lines of Lean