Theorem pm4.71d

Description: Deduction converting an implication to a biconditional with conjunction. Deduction from Theorem *4.71 of WhiteheadRussell p. 120. (Contributed by Mario Carneiro, 25-Dec-2016)

	Ref	Expression
Hypothesis	pm4.71rd.1	|- ( ph -> ( ps -> ch ) )
Assertion	pm4.71d	|- ( ph -> ( ps <-> ( ps /\ ch ) ) )

Proof

Step	Hyp	Ref	Expression
1		pm4.71rd.1	|- ( ph -> ( ps -> ch ) )
2		pm4.71	|- ( ( ps -> ch ) <-> ( ps <-> ( ps /\ ch ) ) )
3	1 2	sylib	|- ( ph -> ( ps <-> ( ps /\ ch ) ) )