Theorem biort 797

Description: A wff is disjoined with truth is true. (Contributed by NM, 23-May-1999.)

Assertion

Ref	Expression
biort	|- ( ph -> ( ph <-> ( ph \/ ps ) ) )

Proof of Theorem biort

Step	Hyp	Ref	Expression
1		orc 684	. 2 |- ( ph -> ( ph \/ ps ) )
2		ax-1 5	. 2 |- ( ph -> ( ( ph \/ ps ) -> ph ) )
3	1, 2	impbid2 142	1 |- ( ph -> ( ph <-> ( ph \/ ps ) ) )

Syntax hints:   -> wi 4   <-> wb 104   \/ wo 680

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 681

This theorem depends on definitions:  df-bi 116

This theorem is referenced by:  pm5.55dc  881