Theorem pm2.61nii

Description: Inference eliminating two antecedents. (Contributed by NM, 13-Jul-2005) (Proof shortened by Andrew Salmon, 25-May-2011) (Proof shortened by Wolf Lammen, 13-Nov-2012)

	Ref	Expression
Hypotheses	pm2.61nii.1	|- ( ph -> ( ps -> ch ) )
	pm2.61nii.2	|- ( -. ph -> ch )
	pm2.61nii.3	|- ( -. ps -> ch )
Assertion	pm2.61nii	|- ch

Proof

Step	Hyp	Ref	Expression
1		pm2.61nii.1	|- ( ph -> ( ps -> ch ) )
2		pm2.61nii.2	|- ( -. ph -> ch )
3		pm2.61nii.3	|- ( -. ps -> ch )
4	1 3	pm2.61d1	|- ( ph -> ch )
5	4 2	pm2.61i	|- ch