Theorem 2rexbii 2398

Description: Inference adding two restricted existential quantifiers to both sides of an equivalence. (Contributed by NM, 11-Nov-1995.)

Hypothesis

Ref	Expression
ralbii.1	|- ( ph <-> ps )

Assertion

Ref	Expression
2rexbii	|- ( E. x e. A E. y e. B ph <-> E. x e. A E. y e. B ps )

Proof of Theorem 2rexbii

Step	Hyp	Ref	Expression
1		ralbii.1	. . 3 |- ( ph <-> ps )
2	1	rexbii 2396	. 2 |- ( E. y e. B ph <-> E. y e. B ps )
3	2	rexbii 2396	1 |- ( E. x e. A E. y e. B ph <-> E. x e. A E. y e. B ps )

Syntax hints:   <-> wb 104   E.wrex 2371

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1388  ax-gen 1390  ax-ie1 1434  ax-ie2 1435  ax-4 1452  ax-17 1471  ax-ial 1479

This theorem depends on definitions:  df-bi 116  df-tru 1299  df-nf 1402  df-rex 2376

This theorem is referenced by:  3reeanv  2551  4fvwrd4  9700