Theorem pm5.12 929

Description: Theorem *5.12 of [WhiteheadRussell] p. 123. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm5.12	|- ( ( ph -> ps ) \/ ( ph -> -. ps ) )

Proof of Theorem pm5.12

Step	Hyp	Ref	Expression
1		pm2.51 165	. 2 |- ( -. ( ph -> ps ) -> ( ph -> -. ps ) )
2	1	orri 391	1 |- ( ( ph -> ps ) \/ ( ph -> -. ps ) )

Syntax hints:   -. wn 3   -> wi 4   \/ wo 383

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-or 385

This theorem is referenced by: (None)