Theorem syl221anc

Description: Syllogism combined with contraction. (Contributed by NM, 11-Mar-2012)

	Ref	Expression
Hypotheses	syl3anc.1	|- ( ph -> ps )
	syl3anc.2	|- ( ph -> ch )
	syl3anc.3	|- ( ph -> th )
	syl3Xanc.4	|- ( ph -> ta )
	syl23anc.5	|- ( ph -> et )
	syl221anc.6	|- ( ( ( ps /\ ch ) /\ ( th /\ ta ) /\ et ) -> ze )
Assertion	syl221anc	|- ( ph -> ze )

Proof

Step	Hyp	Ref	Expression
1		syl3anc.1	|- ( ph -> ps )
2		syl3anc.2	|- ( ph -> ch )
3		syl3anc.3	|- ( ph -> th )
4		syl3Xanc.4	|- ( ph -> ta )
5		syl23anc.5	|- ( ph -> et )
6		syl221anc.6	|- ( ( ( ps /\ ch ) /\ ( th /\ ta ) /\ et ) -> ze )
7	3 4	jca	|- ( ph -> ( th /\ ta ) )
8	1 2 7 5 6	syl211anc	|- ( ph -> ze )