Theorem pm4.56 806

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 669	. 2 |- ( -. ( ph \/ ps ) <-> ( -. ph /\ -. ps ) )
2	1	bicomi 123	1 |- ( ( -. ph /\ -. ps ) <-> -. ( ph \/ ps ) )

Syntax hints:   -. wn 3   /\ wa 97   <-> wb 98   \/ wo 629

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-io 630

This theorem depends on definitions:  df-bi 110

This theorem is referenced by:  oranim  807  neanior  2292  prneimg  3545  nqnq0pi  6536