English
A derivative form of traverse_mul giving equality of two compositions with traverse of a product.
Русский
Другая форма утверждения traverse_mul, выражающая равенство двух композиций с обходом произведения.
LaTeX
$$$\operatorname{traverse} F \circ (\cdot) = \cdot \, \langle \operatorname{traverse} F, \operatorname{traverse} F \rangle$$$
Lean4
@[to_additive (attr := simp)]
theorem traverse_mul' :
Function.comp (traverse F) ∘ (HMul.hMul : FreeSemigroup α → FreeSemigroup α → FreeSemigroup α) = fun x y ↦
(· * ·) <$> traverse F x <*> traverse F y :=
funext fun x ↦ funext fun y ↦ traverse_mul F x y