Equivalently, in a torus divided into regions, it is always possible to color the regions using no more than seven colors so that no neighboring regions are the same color. (Contrast with the four color theorem for the plane.) de Bruijn torus
In combinatorial mathematics, a de Bruijn torus is an array of symbols from an alphabet (often just 0 and 1) that contains every m-by-n matrix exactly once. It is a torus because the edges are considered wraparound for the purpose of finding matrices. Its name comes from the De Bruijn sequence, which can be considered a special case where n is 1 (one dimension).
Rufinamide is an anticonvulsant medication. It is used in combination with other medication and therapy to treat Lennox–Gastaut syndrome and various other seizure disorders. Rufinamide, a triazole derivative, was developed in 2004 by Novartis Pharma, AG, and is manufactured by Eisai. Rufinamide was approved by the US Food and Drug Administration (FDA) on November 14, 2008, as adjunctive treatment of seizures associated with Lennox-Gastaut syndrome in children four years and older and adults. Its official FDA-approved labeling does not mention use in the treatment of partial seizures inasmuch as clinical trials submitted to the FDA were marginal. However, several recent clinical trials suggest that the drug has efficacy for partial seizures  It is marketed under the brand name Banzel. It is also marketed in the European Union under the brand name Inovelon.The mechanism of action of rufinamide is not fully understood. There is some evidence that rufinamide can modulate the gating of voltage-gated sodium channels, a common target for antiepileptic drugs. A recent study indicates subtle effects on the voltage-dependence of gating and the time course of inactivation in some sodium channel isoforms that could reduce neuronal excitability. However, this action cannot explain the unique spectrum of activity of rufinamide. References
External links
"Rufinamide". Drug Information Portal. U.S. National Library of Medicine.