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View Diary: Markos, Ban Snark. (104 comments)

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  •  Definiton of snark (0+ / 0-)

    Snark (graph theory)

    In the mathematical field of graph theory, a snark is a connected, bridgeless cubic graph with chromatic index equal to 4. In other words, it is a graph in which every vertex has three neighbors, and the edges cannot be colored by only three colors without two edges of the same color meeting at a point. (By Vizing's theorem, the chromatic index of a cubic graph is 3 or 4.) In order to avoid trivial cases, snarks are often restricted to have girth at least 5.

    Writing in The Electronic Journal of Combinatorics, Miroslav Chladný states that

    "In the study of various important and difficult problems in graph theory (such as the Cycle double cover conjecture and the 5-Flow Conjecture), one encounters an interesting but somewhat mysterious variety of graphs called snarks. In spite of their simple definition...and over a century long investigation, their properties and structure are largely unknown."

    Stop the NRA and the NSA
    Repeal the Patriot Act and the 2nd Amendment

    by dream weaver on Tue Jun 25, 2013 at 10:19:34 AM PDT

    [ Parent ]

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