An Extremal Property of Turn Graphs, II
Let denote Turn's graphthe complete 2-partite graph on n vertices with partition sizes as equal as possible. We show that for all , the graph has more proper vertex colorings in at most 4 colors than any other graph with the same number of vertices and edges.
turn graph extremal graph number of colorings chromatic polynomial mathematics subject classification: 05c15 05c30 05c31 05c35