English
Let g: γ → δ. Then g'' image2 f s t = image2 (λ a b, g(f a b)) s t.
Русский
Пусть g: γ → δ. Тогда g'' image2 f s t = image2 (λ a b, g(f a b)) s t.
LaTeX
$$$$ g'' \\operatorname{image2} f s t = \\operatorname{image2}(\\lambda a b. g(f(a,b))) s t. $$$$
Lean4
theorem image_image2 (f : α → β → γ) (g : γ → δ) : g '' image2 f s t = image2 (fun a b => g (f a b)) s t := by
simp only [← image_prod, image_image]