English
If s = t, then the identity homeomorphism between s and t is continuous.
Русский
Если s = t, то тождественное гомеоморфизм между s и t непрерывен.
LaTeX
$$$Set.inclusion \\circ id = id \\circ Set.inclusion$$$
Lean4
/-- If two sets are equal, then they are homeomorphic. -/
def setCongr {s t : Set X} (h : s = t) : s ≃ₜ t
where
continuous_toFun := continuous_inclusion h.subset
continuous_invFun := continuous_inclusion h.symm.subset
toEquiv := Equiv.setCongr h