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Theorem stabnot 729
Description: Every formula of the form ¬ φ is stable. Uses notnotnot 615. (Contributed by David A. Wheeler, 13-Aug-2018.)
Assertion
Ref Expression
stabnot STAB ¬ φ

Proof of Theorem stabnot
StepHypRef Expression
1 notnotnot 615 . . 3 (¬ ¬ ¬ φ ↔ ¬ φ)
21biimpi 113 . 2 (¬ ¬ ¬ φ → ¬ φ)
3 df-stab 728 . 2 (STAB ¬ φ ↔ (¬ ¬ ¬ φ → ¬ φ))
42, 3mpbir 134 1 STAB ¬ φ
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  STAB wstab 727
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 532  ax-in2 533
This theorem depends on definitions:  df-bi 110  df-stab 728
This theorem is referenced by: (None)
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