For every graph that is clique equivalent to a connected chordal graph, it is shown that the associated dependence polynomial has a unit root and that the associated clique and independence polynomials have negative unit roots. The dependence polynomial for a graph that is the join of two graphs is also shown to have a unit root when at least one of the two joined graphs is clique equivalent to a connected chordal graph. A condition satisfied by the eigenvalues of graphs that are clique equivalent to connected chordal graphs with clique numbers less than four is identified.
chordal graph, graph polynomial, dependence polynomial, clique polynomial, independence polynomial, graph eigenvalues
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