In [[math]]ematics, a '''union''' of sets is a [[set]] of elements that belong only to the sets. It is denoted A ∪ B and is formally defined as A ∪ B = {x|xϵA OR xϵB}. | In [[math]]ematics, a '''union''' of sets is a [[set]] of elements that belong only to the sets. It is denoted A ∪ B and is formally defined as A ∪ B = {x|xϵA OR xϵB}. |