Theorem ceqsex 2768

Description: Elimination of an existential quantifier, using implicit substitution. (Contributed by NM, 2-Mar-1995.) (Revised by Mario Carneiro, 10-Oct-2016.)

Hypotheses

Ref	Expression
ceqsex.1	|- F/ x ps
ceqsex.2	|- A e. _V
ceqsex.3	|- ( x = A -> ( ph <-> ps ) )

Assertion

Ref	Expression
ceqsex	|- ( E. x ( x = A /\ ph ) <-> ps )

Distinct variable group:   x, A

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

Proof of Theorem ceqsex

Step	Hyp	Ref	Expression
1		ceqsex.1	. . 3 |- F/ x ps
2		ceqsex.3	. . . 4 |- ( x = A -> ( ph <-> ps ) )
3	2	biimpa 294	. . 3 |- ( ( x = A /\ ph ) -> ps )
4	1, 3	exlimi 1587	. 2 |- ( E. x ( x = A /\ ph ) -> ps )
5	2	biimprcd 159	. . . 4 |- ( ps -> ( x = A -> ph ) )
6	1, 5	alrimi 1515	. . 3 |- ( ps -> A. x ( x = A -> ph ) )
7		ceqsex.2	. . . 4 |- A e. _V
8	7	isseti 2738	. . 3 |- E. x x = A
9		exintr 1627	. . 3 |- ( A. x ( x = A -> ph ) -> ( E. x x = A -> E. x ( x = A /\ ph ) ) )
10	6, 8, 9	mpisyl 1439	. 2 |- ( ps -> E. x ( x = A /\ ph ) )
11	4, 10	impbii 125	1 |- ( E. x ( x = A /\ ph ) <-> ps )

Syntax hints:   -> wi 4   /\ wa 103   <-> wb 104   A.wal 1346   = wceq 1348   F/wnf 1453   E.wex 1485   e. wcel 2141   _Vcvv 2730

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1440  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-nf 1454  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-v 2732

This theorem is referenced by:  ceqsexv  2769  ceqsex2  2770