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Theorem nottru 1424
Description: A ¬ identity. (Contributed by Anthony Hart, 22-Oct-2010.)
Assertion
Ref Expression
nottru (¬ ⊤ ↔ ⊥)

Proof of Theorem nottru
StepHypRef Expression
1 df-fal 1370 . 2 (⊥ ↔ ¬ ⊤)
21bicomi 132 1 (¬ ⊤ ↔ ⊥)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wb 105  wtru 1365  wfal 1369
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108
This theorem depends on definitions:  df-bi 117  df-fal 1370
This theorem is referenced by:  truxortru  1430
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