Arc-coloring of directed hypergraphs and chromatic number of walls
نویسنده
چکیده
We define an arc-coloring for directed hypergraphs, such that any two arcs having either intersecting tails or the same head must be colored differently. We investigate the arc-coloring of those hypergraphs which can be represented by suitable adjacency matrices (walls), whereas a polynomial reduction is provided from the general arc-coloring problem to the brick-coloring of walls. An upper bound for the least number of required colors with fixed degree is established for a subclass of hypergraphs. Some particular walls are subsequently analyzed. Key-words: arc-coloring, brick, chromatic index, directed hypergraph, wall. 2000 MSC: 05B99, 05C15, 05C20, 68Q17. ∗Dipartimento Me.Mo.Mat. , Università La Sapienza, via A. Scarpa 16, 00161 Roma, Italia. E-mail: [email protected]
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تاریخ انتشار 2005