Theorem 2oex

Description: 2o is a set. (Contributed by BJ, 6-Apr-2019) Remove dependency on ax-10 , ax-11 , ax-12 , ax-un . (Proof shortened by Zhi Wang, 19-Sep-2024)

	Ref	Expression
Assertion	2oex	⊢ 2o ∈ V

Proof

Step	Hyp	Ref	Expression
1		df2o3	⊢ 2o = { ∅ , 1o }
2		prex	⊢ { ∅ , 1o } ∈ V
3	1 2	eqeltri	⊢ 2o ∈ V