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Theorem drex2 2027
Description: Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of [Megill] p. 448 (p. 16 of preprint). (Contributed by NM, 27-Feb-2005.)
Hypothesis
Ref Expression
dral1.1  |-  ( A. x  x  =  y  ->  ( ph  <->  ps )
)
Assertion
Ref Expression
drex2  |-  ( A. x  x  =  y  ->  ( E. z ph  <->  E. z ps ) )

Proof of Theorem drex2
StepHypRef Expression
1 hbae 2012 . 2  |-  ( A. x  x  =  y  ->  A. z A. x  x  =  y )
2 dral1.1 . 2  |-  ( A. x  x  =  y  ->  ( ph  <->  ps )
)
31, 2exbidh 1644 1  |-  ( A. x  x  =  y  ->  ( E. z ph  <->  E. z ps ) )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 184   A.wal 1368   E.wex 1587
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1592  ax-4 1603  ax-5 1671  ax-6 1710  ax-7 1730  ax-10 1777  ax-11 1782  ax-12 1794  ax-13 1952
This theorem depends on definitions:  df-bi 185  df-an 371  df-ex 1588  df-nf 1591
This theorem is referenced by:  dfid3  4732  dropab1  29838  dropab2  29839  e2ebind  31569
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