Theorem bnj105

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

	Ref	Expression
Assertion	bnj105	⊢ 1o ∈ V

Proof

Step	Hyp	Ref	Expression
1		df1o2	⊢ 1o = { ∅ }
2		p0ex	⊢ { ∅ } ∈ V
3	1 2	eqeltri	⊢ 1o ∈ V