# Definition:Center (Abstract Algebra)/Ring

(Redirected from Definition:Center of Ring)

This page is about Center in the context of Ring Theory. For other uses, see Center.

## Definition

The center of a ring $\struct {R, +, \circ}$, denoted $\map Z R$, is the subset of elements in $R$ that commute under $\circ$ with every element in $R$.

Symbolically:

$\map Z R = \map {C_R} R = \set {x \in R: \forall s \in R: s \circ x = x \circ s}$

That is, the center of $R$ is the centralizer of $R$ in $R$ itself.

It is clear that the center of a ring $\struct {R, +, \circ}$ can be defined as the center of the semigroup $\struct {R, \circ}$.

## Historical Note

The notation $\map Z S$, conventionally used for the center of a structure $\struct {S, \circ}$, derives from the German Zentrum, meaning center.

## Linguistic Note

The British English spelling of center is centre.

The convention on $\mathsf{Pr} \infty \mathsf{fWiki}$ is to use the American English spelling center, but it is appreciated that there may be lapses.