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Metamath Proof Explorer

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