Theorem biantrur

Description: A wff is equivalent to its conjunction with truth. (Contributed by NM, 3-Aug-1994)

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

Proof

Step	Hyp	Ref	Expression
1		biantrur.1	|- ph
2	1	biantru	|- ( ps <-> ( ps /\ ph ) )
3	2	biancomi	|- ( ps <-> ( ph /\ ps ) )