Theorem pm2.61d1

Description: Inference eliminating an antecedent. (Contributed by NM, 15-Jul-2005)

	Ref	Expression
Hypotheses	pm2.61d1.1	|- ( ph -> ( ps -> ch ) )
	pm2.61d1.2	|- ( -. ps -> ch )
Assertion	pm2.61d1	|- ( ph -> ch )

Proof

Step	Hyp	Ref	Expression
1		pm2.61d1.1	|- ( ph -> ( ps -> ch ) )
2		pm2.61d1.2	|- ( -. ps -> ch )
3	2	a1i	|- ( ph -> ( -. ps -> ch ) )
4	1 3	pm2.61d	|- ( ph -> ch )