Theorem n0OLD

Description: Obsolete version of n0 as of 28-Jun-2024. (Contributed by NM, 29-Sep-2006) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	n0OLD	$$⊢A\ne \varnothing \leftrightarrow \exists xx\in A$$

Proof

Step	Hyp	Ref	Expression
1		nfcv	$$⊢\underset{\_}{Ⅎ}xA$$
2	1	n0f	$$⊢A\ne \varnothing \leftrightarrow \exists xx\in A$$