Theorem ecase

Description: Inference for elimination by cases. (Contributed by NM, 13-Jul-2005)

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

Proof

Step	Hyp	Ref	Expression
1		ecase.1	|- ( -. ph -> ch )
2		ecase.2	|- ( -. ps -> ch )
3		ecase.3	|- ( ( ph /\ ps ) -> ch )
4	3	ex	|- ( ph -> ( ps -> ch ) )
5	4 1 2	pm2.61nii	|- ch