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Theorem nbfal 1325
Description: If something is not true, it outputs . (Contributed by Anthony Hart, 14-Aug-2011.)
Assertion
Ref Expression
nbfal φ ↔ (φ ↔ ⊥ ))

Proof of Theorem nbfal
StepHypRef Expression
1 fal 1322 . 2 ¬ ⊥
21nbn 336 1 φ ↔ (φ ↔ ⊥ ))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 176  wfal 1317
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 177  df-tru 1319  df-fal 1320
This theorem is referenced by: (None)
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