Theorem an31s

Description: Swap two conjuncts in antecedent. (Contributed by NM, 31-May-2006)

	Ref	Expression
Hypothesis	an32s.1	|- ( ( ( ph /\ ps ) /\ ch ) -> th )
Assertion	an31s	|- ( ( ( ch /\ ps ) /\ ph ) -> th )

Proof

Step	Hyp	Ref	Expression
1		an32s.1	|- ( ( ( ph /\ ps ) /\ ch ) -> th )
2	1	exp31	|- ( ph -> ( ps -> ( ch -> th ) ) )
3	2	com13	|- ( ch -> ( ps -> ( ph -> th ) ) )
4	3	imp31	|- ( ( ( ch /\ ps ) /\ ph ) -> th )