Theorem pm2.25 419

Description: Theorem *2.25 of [WhiteheadRussell] p. 104. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.25	|- ( ph \/ ( ( ph \/ ps ) -> ps ) )

Proof of Theorem pm2.25

Step	Hyp	Ref	Expression
1		orel1 397	. 2 |- ( -. ph -> ( ( ph \/ ps ) -> ps ) )
2	1	orri 391	1 |- ( ph \/ ( ( ph \/ ps ) -> ps ) )

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

This theorem is referenced by: (None)