Theorem rp-frege24

Description: Introducing an embedded antecedent. Alternate proof for frege24 . Closed form for a1d . (Contributed by RP, 24-Dec-2019)

	Ref	Expression
Assertion	rp-frege24	|- ( ( ph -> ps ) -> ( ph -> ( ch -> ps ) ) )

Proof

Step	Hyp	Ref	Expression
1		rp-simp2-frege	|- ( ph -> ( ps -> ( ch -> ps ) ) )
2		ax-frege2	|- ( ( ph -> ( ps -> ( ch -> ps ) ) ) -> ( ( ph -> ps ) -> ( ph -> ( ch -> ps ) ) ) )
3	1 2	ax-mp	|- ( ( ph -> ps ) -> ( ph -> ( ch -> ps ) ) )