Union_is_Commutative
Provedcommutativityproofwikiset-unionunion-is-commutative
Set union is commutative: S ∪ T = T ∪ S.
Preamble
import Mathlib.Data.Set.Basic
Formal statement
theorem Union_is_Commutative {α : Type*} (S T : Set α) : S ∪ T = T ∪ S := by sorrySource