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	$$⊢\phi$$
Assertion	exgenOLD	$$⊢\exists x\phi$$

Proof

Step	Hyp	Ref	Expression
1		exgen.1	$$⊢\phi$$
2		ax6ev	$$⊢\exists xx=y$$
3	1	a1i	$$⊢x=y\to \phi$$
4	2 3	eximii	$$⊢\exists x\phi$$