Metamath Proof Explorer


Theorem sepnsepolem2

Description: Open neighborhood and neighborhood is equivalent regarding disjointness. Lemma for sepnsepo . Proof could be shortened by 1 step using ssdisjdr . (Contributed by Zhi Wang, 1-Sep-2024)

Ref Expression
Hypothesis sepnsepolem2.1 φ J Top
Assertion sepnsepolem2 φ y nei J D x y = y J D y x y =

Proof

Step Hyp Ref Expression
1 sepnsepolem2.1 φ J Top
2 id J Top J Top
3 sslin z y x z x y
4 sseq0 x z x y x y = x z =
5 4 ex x z x y x y = x z =
6 3 5 syl z y x y = x z =
7 6 adantl J Top z y x y = x z =
8 ineq2 y = z x y = x z
9 8 eqeq1d y = z x y = x z =
10 9 adantl J Top y = z x y = x z =
11 2 7 10 opnneieqv J Top y nei J D x y = y J D y x y =
12 1 11 syl φ y nei J D x y = y J D y x y =