Theorem pm4.56 770

Description: Theorem *4.56 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.56	|- ( ( -. ph /\ -. ps ) <-> -. ( ph \/ ps ) )

Proof of Theorem pm4.56

Step	Hyp	Ref	Expression
1		ioran 742	. 2 |- ( -. ( ph \/ ps ) <-> ( -. ph /\ -. ps ) )
2	1	bicomi 131	1 |- ( ( -. ph /\ -. ps ) <-> -. ( ph \/ ps ) )

Syntax hints:   -. wn 3   /\ wa 103   <-> 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-in1 604  ax-in2 605  ax-io 699

This theorem depends on definitions:  df-bi 116

This theorem is referenced by:  oranim  771  orandc  929  neanior  2423  prneimg  3754  nqnq0pi  7379