English
Inversion on a group-like structure yields an involutive permutation on the underlying set.
Русский
Обратное к группе-подобной структуре образует взаимно однозначную перестановку множества.
LaTeX
$$$\text{Equiv.inv}(G) : G \to G$ is an involutive permutation, i.e., (\text{Equiv.inv}(G))^{2} = id$.$$
Lean4
/-- Inversion on a `Group` or `GroupWithZero` is a permutation of the underlying type. -/
@[to_additive (attr := simps! -fullyApplied apply) /--
Negation on an `AddGroup` is a permutation of the underlying type. -/
]
protected def inv : Perm G :=
inv_involutive.toPerm _