An Upper Bound on the Radius of a 3-Vertex-Connected C4-Free Graph

Abstract

Let G=(V,E) be a finite, connected, undirected graph with vertex set V and edge set E. -e distance dG (u,v) between two vertices u, v of G is the length of a shortest u-v path in G.-e eccentricity ec(v)of a vertex v∈V is the maximum distance between v and any other vertex in G. -e value of the minimum eccentricity of the vertices of G is called the radius of G denoted by rad(G). -e degree deg(v)of a vertex v of G is the number of edges incident with v. -e minimum degree δ(G)is the minimum of the degrees of vertices in G.-e open neighbourhood N(v)of a vertex v is the set of all vertices of G adjacent to v. -e closed neighbourhood N[v]of v is the set N(v)∪v{ }. A graph is triangle-free if it does not contain C3 as a subgraph and C4−free if it does not contain C4 as a subgraph. For notions not defined, here we refer the reader to [1].