Theorem nottru 1518

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

Assertion

Ref	Expression
nottru	|- ( -. T. <-> F. )

Proof of Theorem nottru

Step	Hyp	Ref	Expression
1		df-fal 1489	. 2 |- ( F. <-> -. T. )
2	1	bicomi 214	1 |- ( -. T. <-> F. )

Syntax hints:   -. wn 3   <-> wb 196   T. wtru 1484   F. wfal 1488

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 197  df-fal 1489

This theorem is referenced by:  trunantru  1524  truxortru  1528  falxorfal  1531