An Operator defined on a set which takes two elements from as inputs and returns a single element of . Binary operators are called compositions by Rosenfeld (1968). Sets possessing a binary multiplication operation include the Group, Groupoid, Monoid, Quasigroup, and Semigroup. Sets possessing both a binary multiplication and a binary addition operation include the Division Algebra, Field, Ring, Ringoid, Semiring, and Unit Ring.

**References**

Rosenfeld, A. *An Introduction to Algebraic Structures.* New York: Holden-Day, 1968.

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1999-05-26