Metamath Proof Explorer


Theorem reurab

Description: Restricted existential uniqueness of a restricted abstraction. (Contributed by Scott Fenton, 8-Aug-2024)

Ref Expression
Hypothesis reurab.1
|- ( x = y -> ( ph <-> ps ) )
Assertion reurab
|- ( E! x e. { y e. A | ps } ch <-> E! x e. A ( ph /\ ch ) )

Proof

Step Hyp Ref Expression
1 reurab.1
 |-  ( x = y -> ( ph <-> ps ) )
2 1 bicomd
 |-  ( x = y -> ( ps <-> ph ) )
3 2 equcoms
 |-  ( y = x -> ( ps <-> ph ) )
4 3 elrab
 |-  ( x e. { y e. A | ps } <-> ( x e. A /\ ph ) )
5 4 anbi1i
 |-  ( ( x e. { y e. A | ps } /\ ch ) <-> ( ( x e. A /\ ph ) /\ ch ) )
6 anass
 |-  ( ( ( x e. A /\ ph ) /\ ch ) <-> ( x e. A /\ ( ph /\ ch ) ) )
7 5 6 bitri
 |-  ( ( x e. { y e. A | ps } /\ ch ) <-> ( x e. A /\ ( ph /\ ch ) ) )
8 7 eubii
 |-  ( E! x ( x e. { y e. A | ps } /\ ch ) <-> E! x ( x e. A /\ ( ph /\ ch ) ) )
9 df-reu
 |-  ( E! x e. { y e. A | ps } ch <-> E! x ( x e. { y e. A | ps } /\ ch ) )
10 df-reu
 |-  ( E! x e. A ( ph /\ ch ) <-> E! x ( x e. A /\ ( ph /\ ch ) ) )
11 8 9 10 3bitr4i
 |-  ( E! x e. { y e. A | ps } ch <-> E! x e. A ( ph /\ ch ) )