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Theorem dfral2OLD 2872
Description: Obsolete proof of dfral2 2869 as of 9-Dec-2019. (Contributed by NM, 21-Jan-1997.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
dfral2OLD  |-  ( A. x  e.  A  ph  <->  -.  E. x  e.  A  -.  ph )

Proof of Theorem dfral2OLD
StepHypRef Expression
1 rexnal 2870 . 2  |-  ( E. x  e.  A  -.  ph  <->  -. 
A. x  e.  A  ph )
21con2bii 333 1  |-  ( A. x  e.  A  ph  <->  -.  E. x  e.  A  -.  ph )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    <-> wb 187   A.wral 2771   E.wrex 2772
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1663  ax-4 1676
This theorem depends on definitions:  df-bi 188  df-an 372  df-ex 1658  df-ral 2776  df-rex 2777
This theorem is referenced by: (None)
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