English
For any f and hf, zipWith f hf (single a m) (single a n) = single a (f m n).
Русский
Для любого f и hf, zipWith f hf (single a m) (single a n) = single a (f m n).
LaTeX
$$zipWith f hf (single a m) (single a n) = single a (f m n)$$
Lean4
@[simp]
theorem zipWith_single_single (f : M → N → P) (hf : f 0 0 = 0) (a : α) (m : M) (n : N) :
zipWith f hf (single a m) (single a n) = single a (f m n) :=
by
ext a'
rw [zipWith_apply]
obtain rfl | ha' := eq_or_ne a' a
· rw [single_eq_same, single_eq_same, single_eq_same]
· rw [single_eq_of_ne ha', single_eq_of_ne ha', single_eq_of_ne ha', hf]