Harries graph
Introduction In the mathematical field of graph theory, the '''Harries graph''' or '''Harries (3-10)-cage''' is a 3-regular, undirected graph with 70 vertices and 105 edges.The Harries graph has chromatic number 2, chromatic index 3, radius 6, diameter 6, girth 10 and is Hamiltonian. It is also a 3-vertex-connected and 3-edge-connected, non-planar, cubic graph. It has book thickness 3 and queue number 2.The characteristic polynomial of the Harries graph is:
History In 1972, A. T. Balaban published a (3-10)-cage graph, a cubic graph that has as few vertices as possible for girth 10.It was the first (3-10)-cage discovered but it was not unique.The complete list of (3-10)-cage and the proof of minimality was given by O'Keefe and Wong in 1980.There exist three distinct (3-10)-cage graphs—the Balaban 10-cage, the Harries graph and the Harries–Wong graph. Moreover, the Harries–Wong graph and Harries graph are cospectral graphs.
Gallery Image:Harries graph 2COL.svg|The chromatic number of the Harries graph is 2.Image:Harries graph 3color edge.svg|The chromatic index of the Harries graph is 3.Image:harries_graph_alternative_drawing.svg|Alternative drawing of the Harries graph.Image:Harries graph petersen drawing.jpg|Alternative drawing emphasizing the graph's 4 orbits.
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