Theorem pm4.56 839

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 701	. 2 |- ( -. ( ph \/ ps ) <-> ( -. ph /\ -. ps ) )
2	1	bicomi 130	1 |- ( ( -. ph /\ -. ps ) <-> -. ( ph \/ ps ) )

Syntax hints:   -. wn 3   /\ wa 102   <-> wb 103   \/ wo 661

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 576  ax-in2 577  ax-io 662

This theorem depends on definitions:  df-bi 115

This theorem is referenced by:  oranim  840  orandc  880  neanior  2332  prneimg  3566  nqnq0pi  6628