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Theorem notfal 1396
Description: A ¬ identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.)
Assertion
Ref Expression
notfal (¬ ⊥ ↔ ⊤)

Proof of Theorem notfal
StepHypRef Expression
1 fal 1342 . 2 ¬ ⊥
21bitru 1347 1 (¬ ⊥ ↔ ⊤)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wb 104  wtru 1336  wfal 1340
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605
This theorem depends on definitions:  df-bi 116  df-tru 1338  df-fal 1341
This theorem is referenced by:  truxorfal  1402  falxortru  1403  falxorfal  1404
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