Theorem logic1a

Description: Variant of logic1 . (Contributed by Zhi Wang, 30-Aug-2024)

	Ref	Expression
Hypotheses	pm4.71da.1	|- ( ph -> ( ps <-> ch ) )
	logic1a.2	|- ( ( ph /\ ps ) -> ( th <-> ta ) )
Assertion	logic1a	|- ( ph -> ( ( ps -> th ) <-> ( ch -> ta ) ) )

Proof

Step	Hyp	Ref	Expression
1		pm4.71da.1	|- ( ph -> ( ps <-> ch ) )
2		logic1a.2	|- ( ( ph /\ ps ) -> ( th <-> ta ) )
3	2	ex	|- ( ph -> ( ps -> ( th <-> ta ) ) )
4	1 3	logic1	|- ( ph -> ( ( ps -> th ) <-> ( ch -> ta ) ) )