Theorem 19.2 1617

Description: Theorem 19.2 of [Margaris] p. 89, generalized to use two setvar variables. (Contributed by O'Cat, 31-Mar-2008.)

Assertion

Ref	Expression
19.2	|- ( A. x ph -> E. y ph )

Proof of Theorem 19.2

Step	Hyp	Ref	Expression
1		19.8a 1569	. 2 |- ( ph -> E. y ph )
2	1	sps 1517	1 |- ( A. x ph -> E. y ph )

Syntax hints:   -> wi 4   A.wal 1329   E.wex 1468

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-gen 1425  ax-ie1 1469  ax-ie2 1470  ax-4 1487

This theorem depends on definitions:  df-bi 116

This theorem is referenced by:  i19.24  1618  i19.39  1619  19.34  1662  eusv2i  4371