Theorem simp2bi

Description: Deduce a conjunct from a triple conjunction. (Contributed by Jonathan Ben-Naim, 3-Jun-2011)

	Ref	Expression
Hypothesis	3simp1bi.1	|- ( ph <-> ( ps /\ ch /\ th ) )
Assertion	simp2bi	|- ( ph -> ch )

Proof

Step	Hyp	Ref	Expression
1		3simp1bi.1	|- ( ph <-> ( ps /\ ch /\ th ) )
2	1	biimpi	|- ( ph -> ( ps /\ ch /\ th ) )
3	2	simp2d	|- ( ph -> ch )