Further results on the nullity of signed graphs

The nullity of a graph is the multiplicity of the eigenvalue zero in its spectrum. a signed graph is a graph with a sign attached to each of its edges. in this paper,we apply the coefficient theorem on the characteristic polynomial of a signed graph and give two formulae on the nullity of signed graphs with cut-points. as applications of the above results,we investigate the nullity of the bicyclic signed graph γ ∞ p,q,l,obtain the nullity set of unbalanced bicyclic signed graphs,and thus determine the nullity set of bicyclic signed graphs. © 2014 yu liu and lihua you.