# Commutativity

From Encyclopedia of Mathematics

A property of algebraic operations (cf. Algebraic operation). For addition and multiplication, commutativity is expressed by the formulas
\begin{equation}
a+b=b+a,\quad \text{ and } \quad ab=ba.
\end{equation}
A binary operation $*$ is commutative (or, what is the same, satisfies the law of commutativity) if in the given algebraic system the identity $a*b=b*a$ holds.

**How to Cite This Entry:**

Commutativity.

*Encyclopedia of Mathematics.*URL: http://www.encyclopediaofmath.org/index.php?title=Commutativity&oldid=29184

This article was adapted from an original article by D.M. Smirnov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article