English
Composition of two maps corresponds to the single map of the composition of the functions: map g (map f x) = map (g ∘ f) x.
Русский
Сложение отображений соответствует композиции функций: map g (map f x) = map (g ∘ f) x.
LaTeX
$$$ \\operatorname{map} g (\\operatorname{map} f \\; x) = \\operatorname{map}(g \\circ f) \\; x $$$
Lean4
@[to_additive]
theorem comp {γ : Type w} (f : α → β) (g : β → γ) (x) : map g (map f x) = map (g ∘ f) x := by rcases x with ⟨L⟩;
simp [Function.comp_def]