Theorem pm4.61 415

Description: Theorem *4.61 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.61	|- (-. (ph -> ps) <-> (ph /\ -. ps))

Proof of Theorem pm4.61

Step	Hyp	Ref	Expression
1		annim 414	. 2 |- ((ph /\ -. ps) <-> -. (ph -> ps))
2	1	bicomi 193	1 |- (-. (ph -> ps) <-> (ph /\ -. ps))

Syntax hints:  -. wn 3   -> wi 4   <-> wb 176   /\ 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-an 360

This theorem is referenced by:  pm4.65  416  npss  3380  difin  3493