Definition:Associative Operation

Definition
Let $S$ be a set.

Let $\circ : S \times S \to S$ be a binary operation.

Then $\circ$ is associative :


 * $\forall x, y, z \in S: \left({x \circ y}\right) \circ z = x \circ \left({y \circ z}\right)$

Also see

 * Associativity on Four Elements
 * General Associativity Theorem