English
There is a canonical left embedding inl: M →* M ∗ N given by m ↦ inl m, which preserves the monoid structure.
Русский
Существует каноническое левое вложение inl: M →* M ∗ N, заданное m ↦ inl m, сохраняющее структуру моноида.
LaTeX
$$$ inl: M \to M \ast N \quad\text{is a monoid hom with } inl(mn) = inl(m) \cdot inl(n),\; inl(1)=1.$$$
Lean4
/-- The natural embedding `M →* M ∗ N`. -/
@[to_additive /-- The natural embedding `M →+ AddMonoid.Coprod M N`. -/
]
def inl : M →* M ∗ N where
toFun := fun x => mk (of (.inl x))
map_one' := mk_eq_mk.2 fun _c hc => hc.2.2.1
map_mul' := fun x y => mk_eq_mk.2 fun _c hc => hc.1 x y