Definition:Center (Abstract Algebra)/Semigroup

Definition
The center of a semigroup $\struct {S, \circ}$, denoted $\map Z S$, is the subset of elements in $S$ that commute with every element in $G$.

Symbolically:
 * $\map Z S = \set {s \in S: \forall x \in S: s \circ x = x \circ s}$