Description: The equivalence between neighborhood and open neighborhood. A variant of opnneieqv with two dummy variables. (Contributed by Zhi Wang, 31-Aug-2024)
Ref | Expression | ||
---|---|---|---|
Hypotheses | opnneir.1 | |- ( ph -> J e. Top ) |
|
opnneilv.2 | |- ( ( ph /\ y C_ x ) -> ( ps -> ch ) ) |
||
opnneil.3 | |- ( ( ph /\ x = y ) -> ( ps <-> ch ) ) |
||
Assertion | opnneieqvv | |- ( ph -> ( E. x e. ( ( nei ` J ) ` S ) ps <-> E. y e. J ( S C_ y /\ ch ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | opnneir.1 | |- ( ph -> J e. Top ) |
|
2 | opnneilv.2 | |- ( ( ph /\ y C_ x ) -> ( ps -> ch ) ) |
|
3 | opnneil.3 | |- ( ( ph /\ x = y ) -> ( ps <-> ch ) ) |
|
4 | 1 2 3 | opnneieqv | |- ( ph -> ( E. x e. ( ( nei ` J ) ` S ) ps <-> E. x e. J ( S C_ x /\ ps ) ) ) |
5 | 3 | opnneilem | |- ( ph -> ( E. x e. J ( S C_ x /\ ps ) <-> E. y e. J ( S C_ y /\ ch ) ) ) |
6 | 4 5 | bitrd | |- ( ph -> ( E. x e. ( ( nei ` J ) ` S ) ps <-> E. y e. J ( S C_ y /\ ch ) ) ) |