Theorem rexab2 3266

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
rexab2	|- ( E. x e. { y | ph } ps <-> E. y ( ph /\ ch ) )

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

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

Proof of Theorem rexab2

Step	Hyp	Ref	Expression
1		df-rex 2813	. 2 |- ( E. x e. { y | ph } ps <-> E. x ( x e. { y | ph } /\ ps ) )
2		nfsab1 2446	. . . 4 |- F/ y x e. { y | ph }
3		nfv 1708	. . . 4 |- F/ y ps
4	2, 3	nfan 1929	. . 3 |- F/ y ( x e. { y | ph } /\ ps )
5		nfv 1708	. . 3 |- F/ x ( ph /\ ch )
6		eleq1 2529	. . . . 5 |- ( x = y -> ( x e. { y | ph } <-> y e. { y | ph } ) )
7		abid 2444	. . . . 5 |- ( y e. { y | ph } <-> ph )
8	6, 7	syl6bb 261	. . . 4 |- ( x = y -> ( x e. { y | ph } <-> ph ) )
9		ralab2.1	. . . 4 |- ( x = y -> ( ps <-> ch ) )
10	8, 9	anbi12d 710	. . 3 |- ( x = y -> ( ( x e. { y | ph } /\ ps ) <-> ( ph /\ ch ) ) )
11	4, 5, 10	cbvex 2023	. 2 |- ( E. x ( x e. { y | ph } /\ ps ) <-> E. y ( ph /\ ch ) )
12	1, 11	bitri 249	1 |- ( E. x e. { y | ph } ps <-> E. y ( ph /\ ch ) )

Syntax hints:   -> wi 4   <-> wb 184   /\ wa 369   E.wex 1613   e. wcel 1819   {cab 2442   E.wrex 2808

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1619  ax-4 1632  ax-5 1705  ax-6 1748  ax-7 1791  ax-10 1838  ax-11 1843  ax-12 1855  ax-13 2000  ax-ext 2435

This theorem depends on definitions:  df-bi 185  df-an 371  df-ex 1614  df-nf 1618  df-sb 1741  df-clab 2443  df-cleq 2449  df-clel 2452  df-rex 2813

This theorem is referenced by:  rexrab2  3267  tmdgsum2  20721