Theorem nottru 1348

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 1320	. 2 ⊢ ( ⊥ ↔ ¬ ⊤ )
2	1	bicomi 193	1 ⊢ (¬ ⊤ ↔ ⊥ )

Syntax hints:  ¬ wn 3   ↔ wb 176   ⊤ wtru 1316   ⊥ 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-fal 1320

This theorem is referenced by:  trubifal  1351  trunantru  1354  truxortru  1358  falxorfal  1361