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Theorem notfal 1472
Description: A  -. identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.)
Assertion
Ref Expression
notfal  |-  ( -. F.  <-> T.  )

Proof of Theorem notfal
StepHypRef Expression
1 fal 1444 . 2  |-  -. F.
21bitru 1449 1  |-  ( -. F.  <-> T.  )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    <-> wb 187   T. wtru 1438   F. wfal 1442
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 188  df-tru 1440  df-fal 1443
This theorem is referenced by:  trunanfal  1480  trunanfalOLD  1481  falnanfal  1483  truxorfal  1485  falxortruOLD  1487  ifpdfnan  36100
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