Theorem unisnv

Description: A set equals the union of its singleton (setvar case). (Contributed by NM, 30-Aug-1993)

	Ref	Expression
Assertion	unisnv	$$⊢\bigcup \left\{x\right\}=x$$

Proof

Step	Hyp	Ref	Expression
1		vex	$$⊢x\in \mathrm{V}$$
2	1	unisn	$$⊢\bigcup \left\{x\right\}=x$$