defined on a set S. A function from the domain S × S into S itself. Many of the everyday arithmetic and algebraic operations are dyadic, e.g. the addition of two integers, the union of two sets, and the conjunction of two Boolean expressions. Although basically functions, dyadic operations are usually represented using an infix notation, as in

A symbol, such as ∘, can be used to represent a generalized dyadic operation.

When the set is finite, Cayley tables and sometimes truth tables are used to define the meaning of the operation.