# center -- Returns the center of a graph

## Synopsis

• Usage:
L = center G
• Inputs:
• G, an instance of the type Graph,
• Outputs:
• L, a list, This is a list of the vertices of G that form the center of G

## Description

The center of a graph G is defined to be the set of all vertices of G such that the eccentricity of the vertex is equal to the graph's radius. This list often will contain 1 member, for example, path graphs on with an odd amount of vertices. It can also contain all the vertices (such as complete graphs).

 i1 : center graphLibrary "dart" o1 = {2} o1 : List