Theorem biantru

Description: A wff is equivalent to its conjunction with truth. (Contributed by NM, 26-May-1993)

	Ref	Expression
Hypothesis	biantru.1	|- ph
Assertion	biantru	|- ( ps <-> ( ps /\ ph ) )

Proof

Step	Hyp	Ref	Expression
1		biantru.1	|- ph
2		iba	|- ( ph -> ( ps <-> ( ps /\ ph ) ) )
3	1 2	ax-mp	|- ( ps <-> ( ps /\ ph ) )