Theorem pm4.63 437

Description: Theorem *4.63 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.63	|- ( -. ( ph -> -. ps ) <-> ( ph /\ ps ) )

Proof of Theorem pm4.63

Step	Hyp	Ref	Expression
1		df-an 386	. 2 |- ( ( ph /\ ps ) <-> -. ( ph -> -. ps ) )
2	1	bicomi 214	1 |- ( -. ( ph -> -. ps ) <-> ( ph /\ ps ) )

Syntax hints:   -. wn 3   -> wi 4   <-> wb 196   /\ 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-an 386

This theorem is referenced by:  pm4.67  444  nqereu  9751  axacprim  31584  andnand1  32398