Tutte's edge-colouring conjecture
In 1966 Tutte conjectured that every 2-connected cubic graph not containing the Petersen graph as a minor is 3-edge-colourable. The conjecture is still open, but it is shown in this paper that it is true in general, provided that it is true for two special kinds of cubic graphs that are almost planar.
scientific article; zbMATH DE number 1076877