English
In a commutative group, ((S.leftInvEquiv hS).symm x) equals the inverse of x: ((S.leftInvEquiv hS).symm x : M) = (x : M)^{-1}.
Русский
В коммутативной группе выражение ((S.leftInvEquiv hS).symm x) равно обратному к x.
LaTeX
$$$ ((S.leftInvEquiv hS).symm x : M) = (x : M)^{-1} $$$
Lean4
/-- The center of a semigroup `M` is the set of elements that commute with everything in `M` -/
@[to_additive /-- The center of an additive semigroup `M` is the set of elements that commute with
everything in `M` -/
]
def center : Subsemigroup M where
carrier := Set.center M
mul_mem' := Set.mul_mem_center