English
The composition of two continuous monoid homomorphisms is again a continuous monoid homomorphism.
Русский
Составление двух непрерывных моноид-гомоморфизмов снова даёт непрерывный моноид-гомоморфизм.
LaTeX
$$$g:A\\to_{}^* B$, $f:B\\to_{}^* C$ implies $g\\circ f: A\\to_{}^* C$ is continuous.$$
Lean4
/-- Composition of two continuous homomorphisms. -/
@[to_additive (attr := simps!) /-- Composition of two continuous homomorphisms. -/
]
def comp (g : B →ₜ* C) (f : A →ₜ* B) : A →ₜ* C :=
⟨g.toMonoidHom.comp f.toMonoidHom, (map_continuous g).comp (map_continuous f)⟩