History
P. G. Tait initiated the study of snarks in 1880, when he proved that the four color theorem is equivalent to the statement that no snark is planar. The first known snark was the Petersen graph, discovered in 1898. In 1946, Croatian mathematician Danilo Blanuša discovered two more snarks, both on 18 vertices, now named the Blanuša snarks. The fourth known snark was found two years later by Bill Tutte, under the pseudonym Blanche Descartes, and was a graph of order 210. In 1973, George Szekeres found the fifth known snark — the Szekeres snark. In 1975, Rufus Isaacs generalized Blanuša's method to construct two infinite families of snarks : the flower snark and the BDS or Blanuša–Descartes–Szekeres snark, a family that includes the two Blanuša snarks, the Descartes snark and the Szekeres snark. Isaacs also discovered a 30-vertices snark that does not belong to the BDS family and that is not a flower snark: the double-star snark.
Snarks were so named by the American mathematician Martin Gardner in 1976, after the mysterious and elusive object of the poem The Hunting of the Snark by Lewis Carroll.
Read more about this topic: Snark (graph Theory)
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