Theorem nottru 1424

Description: A ¬ identity. (Contributed by Anthony Hart, 22-Oct-2010.)

Assertion

Ref	Expression
nottru	⊢ (¬ ⊤ ↔ ⊥)

Proof of Theorem nottru

Step	Hyp	Ref	Expression
1		df-fal 1370	. 2 ⊢ (⊥ ↔ ¬ ⊤)
2	1	bicomi 132	1 ⊢ (¬ ⊤ ↔ ⊥)

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