English
Let h: X ≃ₜ Y be a homeomorphism between topological spaces. If X is a normal space, then Y is normal.
Русский
Пусть X и Y — топологические пространства, и h:X ≃ₜ Y — гомеоморфизм. Если X нормальное пространство, то Y нормальное.
LaTeX
$$$ \\forall X,Y\\ [TopologicalSpace X] [TopologicalSpace Y],\\ h:X\\simeq Y\\Rightarrow (NormalSpace X\\Rightarrow NormalSpace Y)$$$
Lean4
protected theorem normalSpace [TopologicalSpace Y] [NormalSpace X] (h : X ≃ₜ Y) : NormalSpace Y :=
h.symm.isClosedEmbedding.normalSpace