Theorem nottru 1509

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 1481	. 2 ⊢ (⊥ ↔ ¬ ⊤)
2	1	bicomi 213	1 ⊢ (¬ ⊤ ↔ ⊥)

Syntax hints:  ¬ wn 3   ↔ wb 195  ⊤wtru 1476  ⊥wfal 1480

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 196  df-fal 1481

This theorem is referenced by:  trunantru  1515  truxortru  1519  falxorfal  1522