## Quick Reference

(of a graph)

A graph may be ‘in several pieces’ and these are called its components: two vertices are in the same component if and only if there is a path from one to the other. A more precise definition can be given by defining an equivalence relation on the set of vertices with *u* equivalent to *v* if there is a path from *u* to *v*. Then the components are the corresponding equivalence classes.

*Subjects:*
Mathematics.