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Theorem 19.23ht 1427
Description: Closed form of Theorem 19.23 of [Margaris] p. 90. (Contributed by NM, 7-Nov-2005.) (Revised by Mario Carneiro, 1-Feb-2015.)
Assertion
Ref Expression
19.23ht  |-  ( A. x ( ps  ->  A. x ps )  -> 
( A. x (
ph  ->  ps )  <->  ( E. x ph  ->  ps )
) )

Proof of Theorem 19.23ht
StepHypRef Expression
1 ax-ie2 1424 1  |-  ( A. x ( ps  ->  A. x ps )  -> 
( A. x (
ph  ->  ps )  <->  ( E. x ph  ->  ps )
) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 103   A.wal 1283   E.wex 1422
This theorem was proved from axioms:  ax-ie2 1424
This theorem is referenced by:  19.23h  1428  exlimd2  1527  19.9ht  1573
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