English
mapAccumr₂ f (xs.snoc x) (ys.snoc y) s = let q := f x y s; let r := mapAccumr₂ f xs ys q.1 in (r.1, r.2.snoc q.2).
Русский
mapAccumr₂ f (xs.snoc x) (ys.snoc y) s = пусть q := f x y s; пусть r := mapAccumr₂ f xs ys q.1; в конце (r.1, r.2.snoc q.2).
LaTeX
$$$\text{mapAccumr₂ } f (xs.snoc x) (ys.snoc y) s =\
\ let q := f x y s \\n let r := mapAccumr₂ f xs ys q.1 \\n \ (r.1, r.2.snoc q.2)$$$
Lean4
@[simp]
theorem mapAccumr₂_snoc (f : α → β → σ → σ × φ) (x : α) (y : β) :
mapAccumr₂ f (xs.snoc x) (ys.snoc y) s =
let q := f x y s
let r := mapAccumr₂ f xs ys q.1
(r.1, r.2.snoc q.2) :=
by induction xs, ys using Vector.inductionOn₂ <;> simp_all