Theorem rexrab2 3374

Description: Existential quantification over a class abstraction. (Contributed by Mario Carneiro, 3-Sep-2015.)

Hypothesis

Ref	Expression
ralab2.1	|- ( x = y -> ( ps <-> ch ) )

Assertion

Ref	Expression
rexrab2	|- ( E. x e. { y e. A | ph } ps <-> E. y e. A ( ph /\ ch ) )

Distinct variable groups:   x, y   x, A   ch, x   ph, x   ps, y

Allowed substitution hints:   ph( y)   ps( x)   ch( y)   A( y)

Proof of Theorem rexrab2

Step	Hyp	Ref	Expression
1		df-rab 2921	. . 3 |- { y e. A | ph } = { y | ( y e. A /\ ph ) }
2	1	rexeqi 3143	. 2 |- ( E. x e. { y e. A | ph } ps <-> E. x e. { y | ( y e. A /\ ph ) } ps )
3		ralab2.1	. . 3 |- ( x = y -> ( ps <-> ch ) )
4	3	rexab2 3373	. 2 |- ( E. x e. { y | ( y e. A /\ ph ) } ps <-> E. y ( ( y e. A /\ ph ) /\ ch ) )
5		anass 681	. . . 4 |- ( ( ( y e. A /\ ph ) /\ ch ) <-> ( y e. A /\ ( ph /\ ch ) ) )
6	5	exbii 1774	. . 3 |- ( E. y ( ( y e. A /\ ph ) /\ ch ) <-> E. y ( y e. A /\ ( ph /\ ch ) ) )
7		df-rex 2918	. . 3 |- ( E. y e. A ( ph /\ ch ) <-> E. y ( y e. A /\ ( ph /\ ch ) ) )
8	6, 7	bitr4i 267	. 2 |- ( E. y ( ( y e. A /\ ph ) /\ ch ) <-> E. y e. A ( ph /\ ch ) )
9	2, 4, 8	3bitri 286	1 |- ( E. x e. { y e. A | ph } ps <-> E. y e. A ( ph /\ ch ) )

Syntax hints:   -> wi 4   <-> wb 196   /\ wa 384   E.wex 1704   e. wcel 1990   {cab 2608   E.wrex 2913   {crab 2916

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-rex 2918  df-rab 2921

This theorem is referenced by:  frminex  5094  sstotbnd3  33575