English
The identity open partial homeomorphism on a space acts as the identity under restriction, i.e., restr_univ for the identity yields itself.
Русский
Идентичный открытый частичный гомоморфизм действует как тождественный при ограничении: restr_univ для тождественного даёт сам тождественный.
LaTeX
$$$\\text{refl}_X: OpenPartialHomeomorph\\ X\\ X$, and $\\text{restr_univ}(\\text{refl}_X) = \\text{refl}_X$$$
Lean4
/-- The identity on the whole space as an open partial homeomorphism. -/
@[simps! (attr := mfld_simps) -fullyApplied apply, simps! -isSimp source target]
protected def refl (X : Type*) [TopologicalSpace X] : OpenPartialHomeomorph X X :=
(Homeomorph.refl X).toOpenPartialHomeomorph