Theorem 1oexOLD

Description: Obsolete version of 1oex as of 19-Sep-2024. (Contributed by BJ, 6-Apr-2019) (Proof shortened by AV, 1-Jul-2022) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	1oexOLD	|- 1o e. _V

Proof

Step	Hyp	Ref	Expression
1		1on	|- 1o e. On
2	1	elexi	|- 1o e. _V