English
There is a natural homomorphism from ENat to Nat sending ∞ to 0, i.e., toNatHom: ENat → Nat with toNatHom = toNat.
Русский
Существует гомоморфизм from ENat to Nat, отправляющий ∞ в 0, т.е. toNatHom: ENat → Nat и toNatHom = toNat.
LaTeX
$$$\\\\operatorname{toNatHom} : \\mathbb{N}_{\\\\infty} \\\\to \\\\mathbb{N},\\\\ toNatHom = toNat.$$$
Lean4
/-- Homomorphism from `ℕ∞` to `ℕ` sending `∞` to `0`. -/
def toNatHom : MonoidWithZeroHom ℕ∞ ℕ where
toFun := toNat
map_one' := rfl
map_zero' := rfl
map_mul' := WithTop.untopD_zero_mul