Theorem 19.44 1675

Description: Theorem 19.44 of [Margaris] p. 90. (Contributed by NM, 12-Mar-1993.)

Hypothesis

Ref	Expression
19.44.1	|- F/ x ps

Assertion

Ref	Expression
19.44	|- ( E. x ( ph \/ ps ) <-> ( E. x ph \/ ps ) )

Proof of Theorem 19.44

Step	Hyp	Ref	Expression
1		19.43 1621	. 2 |- ( E. x ( ph \/ ps ) <-> ( E. x ph \/ E. x ps ) )
2		19.44.1	. . . 4 |- F/ x ps
3	2	19.9 1637	. . 3 |- ( E. x ps <-> ps )
4	3	orbi2i 757	. 2 |- ( ( E. x ph \/ E. x ps ) <-> ( E. x ph \/ ps ) )
5	1, 4	bitri 183	1 |- ( E. x ( ph \/ ps ) <-> ( E. x ph \/ ps ) )

Syntax hints:   <-> wb 104   \/ wo 703   F/wnf 1453   E.wex 1485

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-io 704  ax-5 1440  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-4 1503  ax-ial 1527

This theorem depends on definitions:  df-bi 116  df-nf 1454

This theorem is referenced by:  eeor  1688