Theorem 3anidm23

Description: Inference from idempotent law for conjunction. (Contributed by NM, 1-Feb-2007)

	Ref	Expression
Hypothesis	3anidm23.1	|- ( ( ph /\ ps /\ ps ) -> ch )
Assertion	3anidm23	|- ( ( ph /\ ps ) -> ch )

Proof

Step	Hyp	Ref	Expression
1		3anidm23.1	|- ( ( ph /\ ps /\ ps ) -> ch )
2	1	3expa	|- ( ( ( ph /\ ps ) /\ ps ) -> ch )
3	2	anabss3	|- ( ( ph /\ ps ) -> ch )