Theorem pm4.25 748

Description: Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.25	|- ( ph <-> ( ph \/ ph ) )

Proof of Theorem pm4.25

Step	Hyp	Ref	Expression
1		oridm 747	. 2 |- ( ( ph \/ ph ) <-> ph )
2	1	bicomi 131	1 |- ( ph <-> ( ph \/ ph ) )

Syntax hints:   <-> wb 104   \/ wo 698

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 699

This theorem depends on definitions:  df-bi 116

This theorem is referenced by: (None)