Theorem ccase2 907

Description: Inference for combining cases. (Contributed by NM, 29-Jul-1999.)

Hypotheses

Ref	Expression
ccase2.1	|- ( ( ph /\ ps ) -> ta )
ccase2.2	|- ( ch -> ta )
ccase2.3	|- ( th -> ta )

Assertion

Ref	Expression
ccase2	|- ( ( ( ph \/ ch ) /\ ( ps \/ th ) ) -> ta )

Proof of Theorem ccase2

Step	Hyp	Ref	Expression
1		ccase2.1	. 2 |- ( ( ph /\ ps ) -> ta )
2		ccase2.2	. . 3 |- ( ch -> ta )
3	2	adantr 270	. 2 |- ( ( ch /\ ps ) -> ta )
4		ccase2.3	. . 3 |- ( th -> ta )
5	4	adantl 271	. 2 |- ( ( ph /\ th ) -> ta )
6	4	adantl 271	. 2 |- ( ( ch /\ th ) -> ta )
7	1, 3, 5, 6	ccase 905	1 |- ( ( ( ph \/ ch ) /\ ( ps \/ th ) ) -> ta )

Syntax hints:   -> wi 4   /\ wa 102   \/ wo 661

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 662

This theorem depends on definitions:  df-bi 115

This theorem is referenced by: (None)