Theorem truimfal 1428

Description: A -> identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.)

Assertion

Ref	Expression
truimfal

Proof of Theorem truimfal

Step	Hyp	Ref	Expression
1		tru 1399	. . 3
2	1	a1bi 337	. 2
3	2	bicomi 202	1

Syntax hints:  ->wi 4  <->wb 184  wtru 1396  wfal 1400

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 185  df-tru 1398