# Relation composition

Jump to navigation
Jump to search

In set theory, **composition** is an operation on relations.

Let *R* be a relation between *X* and *Y* and *S* a relation *S* between *Y* and *Z*. The composite relation R.S between *X* and *Z* is defined by

If we equate a relation with its graph, then we may write

Function composition may be regarded as relation composition on functional relations.