Theorem tbtru 1253

Description: A proposition is equivalent to itself being equivalent to T.. (Contributed by Anthony Hart, 14-Aug-2011.)

Assertion

Ref	Expression
tbtru	|- ( ph <-> ( ph <-> T. ) )

Proof of Theorem tbtru

Step	Hyp	Ref	Expression
1		tru 1247	. 2 |- T.
2	1	tbt 236	1 |- ( ph <-> ( ph <-> T. ) )

Syntax hints:   <-> wb 98   T. wtru 1244

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-tru 1246

This theorem is referenced by: (None)