Kernels in quasi-transitive digraphs
Let D be a digraph, V (D) and A (D) will denote the sets of vertices and arcs of D, respectively. A kernel N of D is an independent set of vertices such that for every w is an element of V (D) - N there exists an arc from w to N. A digraph is called quasi-transitive when (u, v) is an element of A (D...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2006 |
| País: | México |
| Institución: | Universidad Nacional Autónoma de México |
| Repositorio: | Sistema de Información de la Facultad de Ciencias, UNAM |
| OAI Identifier: | oai:repositorio.fciencias.unam.mx:11154/1271 |
| Acceso en línea: | http://hdl.handle.net/11154/1271 |
| Access Level: | acceso abierto |
| Palabra clave: | Mathematics kernel kernel-perfect digraph quasi-transitive digraph |
| Sumario: | Let D be a digraph, V (D) and A (D) will denote the sets of vertices and arcs of D, respectively. A kernel N of D is an independent set of vertices such that for every w is an element of V (D) - N there exists an arc from w to N. A digraph is called quasi-transitive when (u, v) is an element of A (D) and (v, w) is an element of A (D) implies (u, v) is an element of A (D) or (w, w) is an element of A (D). This concept was introduced by Ghouila-Houri [Caracterisation des graphes non orientes dont on peut orienter les arretes de maniere a obtenir le graphe d' un relation d'ordre, C.R. Acad. Sci. Paris 254 (1962) 1370-1371] and has been studied by several authors. In this paper the following result is proved: Let D be a digraph. Suppose D = D-1 boolean OR D-2 where D-i is a quasi-transitive digraph which contains no asymmetrical infinite outward path (in D-i) for i is an element of {1, 2} |
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