Theorem axial

Description: The setvar x is not free in A. x ph (intuitionistic logic axiom ax-ial). (Contributed by Jim Kingdon, 31-Dec-2017) (New usage is discouraged.)

	Ref	Expression
Assertion	axial	|- ( A. x ph -> A. x A. x ph )

Proof

Step	Hyp	Ref	Expression
1		hba1	|- ( A. x ph -> A. x A. x ph )