Theorem pm2.73 890

Description: Theorem *2.73 of [WhiteheadRussell] p. 108. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.73	|- ( ( ph -> ps ) -> ( ( ( ph \/ ps ) \/ ch ) -> ( ps \/ ch ) ) )

Proof of Theorem pm2.73

Step	Hyp	Ref	Expression
1		pm2.621 424	. 2 |- ( ( ph -> ps ) -> ( ( ph \/ ps ) -> ps ) )
2	1	orim1d 884	1 |- ( ( ph -> ps ) -> ( ( ( ph \/ ps ) \/ ch ) -> ( ps \/ ch ) ) )

Syntax hints:   -> 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  df-an 386

This theorem is referenced by: (None)