Theorem 19.23v 1929

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 1572	. 2 |- ( ps -> A. x ps )
2	1	19.23h 1544	1 |- ( A. x ( ph -> ps ) <-> ( E. x ph -> ps ) )

Syntax hints:   -> wi 4   <-> wb 105   A.wal 1393   E.wex 1538

This theorem was proved from axioms:  ax-mp 5  ax-gen 1495  ax-ie2 1540  ax-17 1572

This theorem is referenced by:  19.23vv  1930  2eu4  2171  gencbval  2849  euind  2990  reuind  3008  snssb  3801  unissb  3918  disjnim  4073  dftr2  4184  ssrelrel  4819  cotr  5110  dffun2  5328  fununi  5389  dff13  5892  acexmidlem2  5998