Theorem ecase3

Description: Inference for elimination by cases. (Contributed by NM, 23-Mar-1995) (Proof shortened by Wolf Lammen, 26-Nov-2012)

	Ref	Expression
Hypotheses	ecase3.1	|- ( ph -> ch )
	ecase3.2	|- ( ps -> ch )
	ecase3.3	|- ( -. ( ph \/ ps ) -> ch )
Assertion	ecase3	|- ch

Proof

Step	Hyp	Ref	Expression
1		ecase3.1	|- ( ph -> ch )
2		ecase3.2	|- ( ps -> ch )
3		ecase3.3	|- ( -. ( ph \/ ps ) -> ch )
4	1 2	jaoi	|- ( ( ph \/ ps ) -> ch )
5	4 3	pm2.61i	|- ch