Theorem oranabs 901

Description: Absorb a disjunct into a conjunct. (Contributed by Roy F. Longton, 23-Jun-2005.) (Proof shortened by Wolf Lammen, 10-Nov-2013.)

Assertion

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

Proof of Theorem oranabs

Step	Hyp	Ref	Expression
1		biortn 421	. . 3 |- ( ps -> ( ph <-> ( -. ps \/ ph ) ) )
2		orcom 402	. . 3 |- ( ( -. ps \/ ph ) <-> ( ph \/ -. ps ) )
3	1, 2	syl6rbb 277	. 2 |- ( ps -> ( ( ph \/ -. ps ) <-> ph ) )
4	3	pm5.32ri 670	1 |- ( ( ( ph \/ -. ps ) /\ ps ) <-> ( ph /\ ps ) )

Syntax hints:   -. wn 3   <-> wb 196   \/ wo 383   /\ wa 384

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 197  df-or 385  df-an 386

This theorem is referenced by:  itg2addnclem3  33463