Theorem pm4.53 478

Description: Theorem *4.53 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.53	|- (-. (ph /\ -. ps) <-> (-. ph \/ ps))

Proof of Theorem pm4.53

Step	Hyp	Ref	Expression
1		pm4.52 477	. . 3 |- ((ph /\ -. ps) <-> -. (-. ph \/ ps))
2	1	con2bii 322	. 2 |- ((-. ph \/ ps) <-> -. (ph /\ -. ps))
3	2	bicomi 193	1 |- (-. (ph /\ -. ps) <-> (-. ph \/ ps))

Syntax hints:  -. wn 3   <-> wb 176   \/ wo 357   /\ wa 358

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 177  df-or 359  df-an 360

This theorem is referenced by:  undif3  3516