Theorem pm2.621 666

Description: Theorem *2.621 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.) (Revised by NM, 13-Dec-2013.)

Assertion

Ref	Expression
pm2.621	|- ( ( ph -> ps ) -> ( ( ph \/ ps ) -> ps ) )

Proof of Theorem pm2.621

Step	Hyp	Ref	Expression
1		id 19	. 2 |- ( ( ph -> ps ) -> ( ph -> ps ) )
2		idd 21	. 2 |- ( ( ph -> ps ) -> ( ps -> ps ) )
3	1, 2	jaod 637	1 |- ( ( ph -> ps ) -> ( ( ph \/ ps ) -> ps ) )

Syntax hints:   -> wi 4   \/ wo 629

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630

This theorem depends on definitions:  df-bi 110

This theorem is referenced by:  pm2.62  667  pm2.73  719  pm4.72  736  undif4  3284