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Theorem nbfal 1316
Description: If something is not true, it outputs  F.. (Contributed by Anthony Hart, 14-Aug-2011.)
Assertion
Ref Expression
nbfal  |-  ( -. 
ph 
<->  ( ph  <->  F.  )
)

Proof of Theorem nbfal
StepHypRef Expression
1 fal 1313 . 2  |-  -.  F.
21nbn 336 1  |-  ( -. 
ph 
<->  ( ph  <->  F.  )
)
Colors of variables: wff set class
Syntax hints:   -. wn 3    <-> wb 176    F. wfal 1308
This theorem is referenced by:  zfnuleu  4162  bisym1  24930  aisfina  27969  aibnbna  27977
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
This theorem depends on definitions:  df-bi 177  df-tru 1310  df-fal 1311
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