(thing) by Orange Julius Sat Jul 08 2000 at 16:42:49
Union. Given two sets A and B, A ∪ B consists of the set containing all elements in either A or B. Another simplistic example:

A = { 1, 3, 5, 7 }
B = { 2, 4, 6, 8 }

A ∪ B = { 1, 2, 3, 4, 5, 6, 7, 8 }

∪ is written in HTML as ∪
See also: ∩

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