Theorem pm2.6 182

Description: Theorem *2.6 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.6	|- ( ( -. ph -> ps ) -> ( ( ph -> ps ) -> ps ) )

Proof of Theorem pm2.6

Step	Hyp	Ref	Expression
1		id 22	. 2 |- ( ( -. ph -> ps ) -> ( -. ph -> ps ) )
2		idd 24	. 2 |- ( ( -. ph -> ps ) -> ( ps -> ps ) )
3	1, 2	jad 174	1 |- ( ( -. ph -> ps ) -> ( ( ph -> ps ) -> ps ) )

Syntax hints:   -. wn 3   -> wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem is referenced by:  pm2.61  183