Theorem exgenOLD

Description: Obsolete version of exgen as of 20-Oct-2023. (Contributed by Wolf Lammen, 12-Nov-2017) (Proof shortened by Wolf Lammen, 9-Dec-2017) (New usage is discouraged.) (Proof modification is discouraged.)

	Ref	Expression
Hypothesis	exgen.1	|- ph
Assertion	exgenOLD	|- E. x ph

Proof

Step	Hyp	Ref	Expression
1		exgen.1	|- ph
2		ax6ev	|- E. x x = y
3	1	a1i	|- ( x = y -> ph )
4	2 3	eximii	|- E. x ph