Theorem 3anidm13

Description: Inference from idempotent law for conjunction. (Contributed by NM, 7-Mar-2008)

	Ref	Expression
Hypothesis	3anidm13.1	|- ( ( ph /\ ps /\ ph ) -> ch )
Assertion	3anidm13	|- ( ( ph /\ ps ) -> ch )

Proof

Step	Hyp	Ref	Expression
1		3anidm13.1	|- ( ( ph /\ ps /\ ph ) -> ch )
2	1	3com23	|- ( ( ph /\ ph /\ ps ) -> ch )
3	2	3anidm12	|- ( ( ph /\ ps ) -> ch )