On the invariance of Colin de Verdièreʹs graph parameter under clique sums Original Research Article

For any undirected graph G, let μ(G) be the graph invariant introduced by Colin de Verdière. In this paper we study the behavior of μ(G) under clique sums of graphs. In particular, we give a forbidden minor characterization of those clique sums G of G1 and G2 for which μ(G) = max{μ(G1), μ(G2)}.