Theorem pm2.67-2 404

Description: Slight generalization of Theorem *2.67 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.67-2	|- ( ( ( ph \/ ch ) -> ps ) -> ( ph -> ps ) )

Proof of Theorem pm2.67-2

Step	Hyp	Ref	Expression
1		orc 387	. 2 |- ( ph -> ( ph \/ ch ) )
2	1	imim1i 60	1 |- ( ( ( ph \/ ch ) -> ps ) -> ( ph -> ps ) )

Syntax hints:   -> wi 4   \/ wo 370

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 189  df-or 372

This theorem is referenced by:  pm2.67  405  jaob  791