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Theorem nbfal 1334
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 1331 . 2  |-  -.  F.
21nbn 337 1  |-  ( -. 
ph 
<->  ( ph  <->  F.  )
)
Colors of variables: wff set class
Syntax hints:   -. wn 3    <-> wb 177    F. wfal 1326
This theorem is referenced by:  zfnuleu  4327  bisym1  26161  aisfina  27833
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 178  df-tru 1328  df-fal 1329
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