Theorem pm5.12 665

Description: Theorem *5.12 of [WhiteheadRussell] p. 123.

Assertion

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

Proof of Theorem pm5.12

Step	Hyp	Ref	Expression
1		pm2.51 101	. 2 |- (-. (ph -> ps) -> (ph -> -. ps))
2	1	orri 231	1 |- ((ph -> ps) \/ (ph -> -. ps))

Syntax hints:  -. wn 2   -> wi 3   \/ wo 222

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7

This theorem depends on definitions:  df-bi 147  df-or 224

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