Metamath Proof Explorer


Theorem iscnrm3lem1

Description: Lemma for iscnrm3 . Subspace topology is a topology. (Contributed by Zhi Wang, 3-Sep-2024)

Ref Expression
Assertion iscnrm3lem1
|- ( J e. Top -> ( A. x e. A ph <-> A. x e. A ( ( J |`t x ) e. Top /\ ph ) ) )

Proof

Step Hyp Ref Expression
1 resttop
 |-  ( ( J e. Top /\ x e. A ) -> ( J |`t x ) e. Top )
2 1 biantrurd
 |-  ( ( J e. Top /\ x e. A ) -> ( ph <-> ( ( J |`t x ) e. Top /\ ph ) ) )
3 2 ralbidva
 |-  ( J e. Top -> ( A. x e. A ph <-> A. x e. A ( ( J |`t x ) e. Top /\ ph ) ) )