Star Complements and Maximal Exceptional Graphs
نویسندگان
چکیده
If G is a maximal exceptional graph then either (a) G is the cone over a graph switching-equivalent to the line graph L(K8) or (b) G has K8 as a star complement for the eigenvalue −2 (or both). In case (b) it is shown how G can be constructed from K8 using intersecting families of 3-sets.
منابع مشابه
Star complements and exceptional graphs
Let G be a finite graph of order n with an eigenvalue μ of multiplicity k. (Thus the μ-eigenspace of a (0, 1)-adjacency matrix of G has dimension k.) A star complement for μ in G is an induced subgraph G−X of G such that |X| = k and G−X does not have μ as an eigenvalue. An exceptional graph is a connected graph, other than a generalized line graph, whose eigenvalues lie in [−2,∞). We establish ...
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