Theorem 19.23v 1894

Description: Special case of Theorem 19.23 of [Margaris] p. 90. (Contributed by NM, 28-Jun-1998.)

Assertion

Ref	Expression
19.23v	|- ( A. x ( ph -> ps ) <-> ( E. x ph -> ps ) )

Distinct variable group:   ps, x

Allowed substitution hint:   ph( x)

Proof of Theorem 19.23v

Step	Hyp	Ref	Expression
1		ax-17 1537	. 2 |- ( ps -> A. x ps )
2	1	19.23h 1509	1 |- ( A. x ( ph -> ps ) <-> ( E. x ph -> ps ) )

Syntax hints:   -> wi 4   <-> wb 105   A.wal 1362   E.wex 1503

This theorem was proved from axioms:  ax-mp 5  ax-gen 1460  ax-ie2 1505  ax-17 1537

This theorem is referenced by:  19.23vv  1895  2eu4  2135  gencbval  2809  euind  2948  reuind  2966  snssb  3752  unissb  3866  disjnim  4021  dftr2  4130  ssrelrel  4760  cotr  5048  dffun2  5265  fununi  5323  dff13  5812  acexmidlem2  5916