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Theorem 19.3v 1678
Description: Special case of Theorem 19.3 of [Margaris] p. 89. Revised to remove dependency on ax-8 1688. (Contributed by NM, 1-Aug-2017.) (Revised by Wolf Lammen, 4-Dec-2017.)
Assertion
Ref Expression
19.3v  |-  ( A. x ph  <->  ph )
Distinct variable group:    ph, x

Proof of Theorem 19.3v
StepHypRef Expression
1 alex 1582 . 2  |-  ( A. x ph  <->  -.  E. x  -.  ph )
2 19.9v 1677 . . 3  |-  ( E. x  -.  ph  <->  -.  ph )
32con2bii 324 . 2  |-  ( ph  <->  -. 
E. x  -.  ph )
41, 3bitr4i 245 1  |-  ( A. x ph  <->  ph )
Colors of variables: wff set class
Syntax hints:   -. wn 3    <-> wb 178   A.wal 1550   E.wex 1551
This theorem is referenced by:  spvw  1679  19.9vOLD  1711  axrep1  4324  kmlem14  8048  quantriv  26155  dford4  27114
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1556  ax-5 1567  ax-17 1627  ax-9 1667
This theorem depends on definitions:  df-bi 179  df-an 362  df-ex 1552
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