Theorem pm5.12 855

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		pm2.51 145	. 2 |- (-. (ph -> ps) -> (ph -> -. ps))
2	1	orri 365	1 |- ((ph -> ps) \/ (ph -> -. ps))

Syntax hints:  -. wn 3   -> wi 4   \/ wo 357

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-or 359

This theorem is referenced by: (None)