Theorem nottru 1567

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 1553	. 2 ⊢ (⊥ ↔ ¬ ⊤)
2	1	bicomi 224	1 ⊢ (¬ ⊤ ↔ ⊥)

Syntax hints:  ¬ wn 3   ↔ wb 206  ⊤wtru 1541  ⊥wfal 1552

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 207  df-fal 1553

This theorem is referenced by:  trunantru  1581  truxortru  1585  falxorfal  1588