In the mathematical field of graph theory, a Descartes snark is an undirected graph with 210 vertices and 315 edges.

It is a snark, a graph with three edges at each vertex that cannot be partitioned into three perfect matchings.

It was first discovered by William Tutte in 1948 under the pseudonym Blanche Descartes.

[1] A Descartes snark is obtained from the Petersen graph by replacing each vertex with a nonagon and each edge with a particular graph closely related to the Petersen graph.

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