English
The composition of snd with map f g equals the composition of g with snd: snd ∘ map f g = g ∘ snd.
Русский
Составление snd с map f g равно составлению g с snd: snd ∘ map f g = g ∘ snd.
LaTeX
$$$$ \\mathrm{Prod.snd} \\circ \\mathrm{Prod.map} \\; f \\; g = g \\circ \\mathrm{Prod.snd} $$$$
Lean4
theorem map_snd' (f : α → γ) (g : β → δ) : Prod.snd ∘ map f g = g ∘ Prod.snd :=
funext <| map_snd f g