English
Composition of OneHom is associative: composing f,g,h yields the same as (h ∘ g) ∘ f = h ∘ (g ∘ f).
Русский
Компоновка OneHom ассоциативна: (h ∘ g) ∘ f = h ∘ (g ∘ f).
LaTeX
$$$ (h \\circ g) \\circ f = h \\circ (g \\circ f) $$$
Lean4
/-- Composition of monoid homomorphisms is associative. -/
@[to_additive /-- Composition of additive monoid homomorphisms is associative. -/
]
theorem comp_assoc {Q : Type*} [One M] [One N] [One P] [One Q] (f : OneHom M N) (g : OneHom N P) (h : OneHom P Q) :
(h.comp g).comp f = h.comp (g.comp f) :=
rfl