In this paper we examine
the relation between B-sets, which are a purely set-theoretic concept, and various
concepts associated with planar maps, for instance, four-colorings, five-colorings,
Hamiltonian circuits, and Petersen’s theorem. Moreover, the introduction of
the notion of a B-set into graph theory enables us to ask questions which
may be more tractable than the four-color conjecture and shed light on
it.
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