Theorem pm2.61i

Description: Inference eliminating an antecedent. (Contributed by NM, 5-Apr-1994) (Proof shortened by Wolf Lammen, 19-Nov-2023)

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

Proof

Step	Hyp	Ref	Expression
1		pm2.61i.1	|- ( ph -> ps )
2		pm2.61i.2	|- ( -. ph -> ps )
3	1 2	nsyl4	|- ( -. ps -> ps )
4	3	pm2.18i	|- ps