Very well-covered graphs with log-concave independence polynomials
Abstract
If for any the -th coefficient of a polynomial is equal to the number of stable sets of cardinality in the graph , then it is called the independence polynomial of (Gutman and Harary, 1983). Alavi, Malde, Schwenk and Erdos (1987) conjectured that is unimodal, whenever is a forest, while Brown, Dilcher and Nowakowski (2000) conjectured that is unimodal for any well-covered graph G. Michael and Traves (2003) showed that the assertion is false for well-covered graphs with > 3 ( is the size of a maximum stable set of the graph ), while for very well-covered graphs the conjecture is still open. In this paper we give support to both conjectures by demonstrating that if < 4, or belongs to , then is log-concave, and, hence, unimodal (where is the very well-covered graph obtained from by appending a single pendant edge to each vertex).
Cite
@article{arxiv.math/0411239,
title = {Very well-covered graphs with log-concave independence polynomials},
author = {Vadim E. Levit and Eugen Mandrescu},
journal= {arXiv preprint arXiv:math/0411239},
year = {2011}
}
Comments
8 pages, 4 figures