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Snark Superposition


A snark superposition is a graph construction that starts with a connected cubic graph G and replaces its vertices and edges by cubic graph multipoles called supervertices and superedges, respectively. Each supervertex has three connectors, one for each incident edge of G, and each superedge is a graph dipole. Joining corresponding connectors produces a cubic graph that retains the incidence pattern of G (Máčajová and Škoviera 2021).

A snark superposition is proper if its base graph is a snark and every superedge is proper. A superedge is proper if, for every nowhere-zero Z_2×Z_2-flow on its graph dipole, the total flow through each connector is nonzero. Every connected proper snark superposition is a snark (Máčajová and Škoviera 2021).

The Descartes snarks are early examples of proper snark superposition. Their base graph is the Petersen graph, their supervertices are 9-cycles, and their superedges are proper (3,3)-graph dipoles obtained by deleting two vertices at distance 2 from the Petersen graph (Descartes 1948, Máčajová and Škoviera 2021).


See also

Cubic Graph, Descartes Snarks, Graph Dipole, Graph Multipole, Petersen Graph, Snark, Superposition Principle

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References

Descartes, B. "Network-Colourings." Math. Gaz. 32, 67-69, 1948.Máčajová, E. and Škoviera, M. "Superposition of Snarks Revisited." European J. Combin. 91, 103220, 2021. https://doi.org/10.1016/j.ejc.2020.103220.

Cite this as:

Weisstein, Eric W. "Snark Superposition." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/SnarkSuperposition.html

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