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Johnson Skeleton Graph


JohnsonSkeletonGraphs

The name "Johnson skeleton graphs" is used for the skeletons of the Johnson solids, which are polyhedral graphs.

Special cases are summarized in the following table.

The Johnson skeleton graphs J_3 and J_(63) are minimal forbidden graphs for unit-distance graphs.

The Johnson skeleton graphs J_(10), J_(17), J_(85), and J_(90) contain induced subgraphs admitting partial proper colorings using four colors that tangle the Kempe chains in the original two-interchange argument of Kempe's coloring algorithm. They have 9, 10, 16, and 16 vertices, respectively, and are the skeletons of the gyroelongated square pyramid, gyroelongated square dipyramid, snub square antiprism, and disphenocingulum. The Fritsch graph, corresponding to J_(51), is another such example. Note that these obstructions to Kempe's argument do not imply that the Kempe-Kittell coloring algorithm fails.

The skeleton of the gyroelongated pentagonal pyramid J_(11) appeared in Zaks (1976) and was used by Owens (1980) in the construction of a 76-node polyhedral quintic nonhamiltonian graph (though neither author identified the graph as the skeleton of a particular polyhedron).

An unrelated family of graphs known as Johnson graphs J(n,k) is defined as graphs whose vertices are given by the k-subsets of {1,...,n}, with two vertices adjacent iff their intersection has size k-1.

The Johnson skeleton graph J_(26) is an outer-cylindrical forbidden minor theta_6 (No. 36; Archdeacon et al. 2001).


See also

Johnson Graph, Johnson Solid, Kempe Chain, Kempe's Coloring Algorithm, Outer-Cylindrical Graph

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References

Archdeacon, D.; Bonnington, C. P.; Dean, N.; Hartsfield, N.; and Scott, K. "Obstruction Sets for Outer-Cylindrical Graphs." J. Graph Th. 38, 42-64, 2001. https://doi.org/10.1002/jgt.1023.House of Graphs. Johnson Skeleton Graphs. Triangular Cupola, Pyramid graph, Gyroelongated square bipyramid, Snub Square Antiprism, K3 x K3 - v, Medial of the Herschel graph, Graph 57269, and others.Owens, P. J. "On Regular Graphs and Hamiltonian Circuits, Including Answers to Some Questions of Joseph Zaks." J. Combin. Theory, Ser. B 28, 262-277, 1980.Zaks, J. "Pairs of Hamiltonian Circuits in 5-Connected Planar Graphs." J. Combin. Th. Ser. B, 116-131, 1976.

Referenced on Wolfram|Alpha

Johnson Skeleton Graph

Cite this as:

Weisstein, Eric W. "Johnson Skeleton Graph." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/JohnsonSkeletonGraph.html

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