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Theorem eubi 27305
Description: Theorem *14.271 in [WhiteheadRussell] p. 192. (Contributed by Andrew Salmon, 11-Jul-2011.)
Assertion
Ref Expression
eubi  |-  ( A. x ( ph  <->  ps )  ->  ( E! x ph  <->  E! x ps ) )

Proof of Theorem eubi
StepHypRef Expression
1 nfa1 1796 . 2  |-  F/ x A. x ( ph  <->  ps )
2 sp 1755 . 2  |-  ( A. x ( ph  <->  ps )  ->  ( ph  <->  ps )
)
31, 2eubid 2245 1  |-  ( A. x ( ph  <->  ps )  ->  ( E! x ph  <->  E! x ps ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177   A.wal 1546   E!weu 2238
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1552  ax-5 1563  ax-17 1623  ax-9 1661  ax-8 1682  ax-6 1736  ax-11 1753
This theorem depends on definitions:  df-bi 178  df-ex 1548  df-nf 1551  df-eu 2242
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