Theorem nottru 1304

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 1249	. 2 ⊢ (⊥ ↔ ¬ ⊤)
2	1	bicomi 123	1 ⊢ (¬ ⊤ ↔ ⊥)

Syntax hints:  ¬ wn 3   ↔ wb 98  ⊤wtru 1244  ⊥wfal 1248

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101

This theorem depends on definitions:  df-bi 110  df-fal 1249

This theorem is referenced by:  truxortru  1310