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Theorem r19.23vOLD 2948
Description: Obsolete proof of r19.23v 2947 as of 12-Jan-2020. (Contributed by NM, 31-Aug-1999.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
r19.23vOLD  |-  ( A. x  e.  A  ( ph  ->  ps )  <->  ( E. x  e.  A  ph  ->  ps ) )
Distinct variable group:    ps, x
Allowed substitution hints:    ph( x)    A( x)

Proof of Theorem r19.23vOLD
StepHypRef Expression
1 nfv 1683 . 2  |-  F/ x ps
21r19.23 2946 1  |-  ( A. x  e.  A  ( ph  ->  ps )  <->  ( E. x  e.  A  ph  ->  ps ) )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 184   A.wral 2817   E.wrex 2818
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1601  ax-4 1612  ax-5 1680  ax-6 1719  ax-7 1739  ax-10 1786  ax-12 1803
This theorem depends on definitions:  df-bi 185  df-an 371  df-ex 1597  df-nf 1600  df-ral 2822  df-rex 2823
This theorem is referenced by: (None)
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