Theorem unisnv

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

	Ref	Expression
Assertion	unisnv	⊢ ∪ { 𝑥 } = 𝑥

Proof

Step	Hyp	Ref	Expression
1		vex	⊢ 𝑥 ∈ V
2	1	unisn	⊢ ∪ { 𝑥 } = 𝑥