Contents

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Characterization of M3(2)-graphs

S. Akbari1, D. Kiani2,3, F. Mohammadi2, S. Moradi2
1Department of Mathematical Sciences Sharif University of Technology P. O. Box 11365-9415, Tehran, Iran.
2Department of Pure Mathematics, Faculty of Mathematics and Computer Sci- ence, Amirkabir University of Technology (Tehran Polytechnic), 424, Hafez Ave., Tehran 15914, Iran.
3Institute for Studies in Theoretical Physics and Mathematics (IPM).

Abstract

A graph G is called an Mr(k)-graph if G has no k-list assignment to its vertices with exactly r vertex colorings. We characterize all M3(2)-graphs. More precisely, it is shown that a connected graph G is an M3(2)-graph if and only if each block of G is a complete graph with at least three vertices.