Theorem tbtru 1363

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 1357	. 2 |- T.
2	1	tbt 247	1 |- ( ph <-> ( ph <-> T. ) )

Syntax hints:   <-> wb 105   T. wtru 1354

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108

This theorem depends on definitions:  df-bi 117  df-tru 1356

This theorem is referenced by: (None)