Theorem pm2.64 830

Description: Theorem *2.64 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.64	|- ( ( ph \/ ps ) -> ( ( ph \/ -. ps ) -> ph ) )

Proof of Theorem pm2.64

Step	Hyp	Ref	Expression
1		orel2 398	. . 3 |- ( -. ps -> ( ( ph \/ ps ) -> ph ) )
2	1	jao1i 825	. 2 |- ( ( ph \/ -. ps ) -> ( ( ph \/ ps ) -> ph ) )
3	2	com12 32	1 |- ( ( ph \/ ps ) -> ( ( ph \/ -. ps ) -> ph ) )

Syntax hints:   -. wn 3   -> 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:  hirstL-ax3  41059