Enzo Maria Li Marzi, Maria Corinna Marino
We consider the maximal planar graphs Gn
=(X,S), |X|=n, and the set of the triangular faces T of Gn
In this paper, HT
is a mixed hypergraph, each element of T is both an edge and a co-edge as in the terminology introduced by Voloshin.
We prove that the lower chromatic number of such hypergraphs is 2 and we determine the upper bound for the upper chromatic number, that is reached by some classes of these hypergraphs.
In 3. the chromatic spectrum is studied and it is proved that, in some cases, it is not broken.
E.M. Li Marzi, M.C. Marino,
Department of Mathematics, University of Messina,
Contrada Papardo, Salita Sperone 31,
98166 - Sant'Agata - Messina
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