Table of Contents
ISRN Combinatorics
Volume 2013 (2013), Article ID 243981, 6 pages
http://dx.doi.org/10.1155/2013/243981
Research Article

Lexicographic Product and Isoperimetric Number

1Turgutlu Vocational Training School, Celal Bayar University, Turgutlu-Manisa, Turkey
2Department of Mathematics, Ege University, Izmir, Turkey

Received 26 June 2013; Accepted 28 July 2013

Academic Editors: M. Caramia, P. E. Jorgensen, and S. Richter

Copyright © 2013 Ersin Aslan and Alpay Kirlangic. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The isoperimetric number of a graph , denoted by , was introduced by Mohar (1987). A graph and a subset of its vertices are given, and let denote the edge boundary of , the set of edges which connects vertices in to vertices not in . The isoperimetric number of is defined as . In this paper, some results about the isoperimetric number of graphs obtained by graph operations are given.