Metamath Proof Explorer


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 1 𝑜 V

Proof

Step Hyp Ref Expression
1 1on 1 𝑜 On
2 1 elexi 1 𝑜 V