English
Let α be a type. There exists a natural equivalence between α and Multiplicative α, given by the identity on the underlying elements.
Русский
Пусть α — множество. Существует естественное эквивалентство между α и Multiplicative α, задаваемое идентичностью на элементарной основе.
LaTeX
$$$\alpha \cong \mathrm{Multiplicative}\,\alpha$$$
Lean4
/-- Reinterpret `x : α` as an element of `Multiplicative α`. -/
def ofAdd : α ≃ Multiplicative α :=
⟨fun x => x, fun x => x, fun _ => rfl, fun _ => rfl⟩