English
Left multiplication by any element a in G is a homeomorphism G → G.
Русский
Левое умножение на произвольный элемент a в группе G является гомеоморфизмом G → G.
LaTeX
$$$\\forall a\\in G:\\ (x\\mapsto a x) \\text{ is a homeomorphism } G \\to G.$$$
Lean4
/-- Multiplication from the left in a topological group as a homeomorphism. -/
@[to_additive /-- Addition from the left in a topological additive group as a homeomorphism. -/
]
protected def mulLeft (a : G) : G ≃ₜ G :=
{ Equiv.mulLeft a with
continuous_toFun := continuous_const.mul continuous_id
continuous_invFun := continuous_const.mul continuous_id }