Enviaments recents

  • The degree/diameter problem in maximal planar bipartite graphs 

    Dalfó Simó, Cristina; Huemer, Clemens; Salas Piñon, Julián (2016)
    Article
    Accés obert
    The (Δ,D)(Δ,D) (degree/diameter) problem consists of finding the largest possible number of vertices nn among all the graphs with maximum degree ΔΔ and diameter DD. We consider the (Δ,D)(Δ,D) problem for maximal planar ...
  • Perfect and quasiperfect domination in trees 

    Cáceres, José; Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Puertas, Maria Luz (2016-04-25)
    Article
    Accés obert
    A k quasip erfect dominating set of a connected graph G is a vertex subset S such that every vertex not in S is adjacent to at least one and at most k vertices in S . The cardinality of a minimum k-quasip erfect dominating ...
  • Opening the black box of energy throughputs in farm systems: a decomposition analysis between the energy returns to external inputs, internal biomass reuses and total inputs consumed (the Vallès County, Catalonia, c.1860 and 1999) 

    Tello, E.; Galán, E.; Sacristán Adinolfi, Vera; Cunfer, G.; Guzmán, G. I.; González de Molina, M.; Krausmann, F.; Gringrich, S.; Padró, R.; Marco, I.; Moreno-Delgado, D. (2016)
    Article
    Accés restringit per política de l'editorial
    We present an energy analysis of past and present farm systems aimed to contribute to their sustainability assessment. Looking at agroecosystems as a set of energy loops between nature and society, and adopting a farm-operator ...
  • Lower bounds on the maximum number of non-crossing acyclic graphs 

    Huemer, Clemens; Mier Vinué, Anna de (2015-08-01)
    Article
    Accés restringit per política de l'editorial
    This paper is a contribution to the problem of counting geometric graphs on point sets. More concretely, we look at the maximum numbers of non-crossing spanning trees and forests. We show that the so-called double chain ...
  • On k-gons and k-holes in point sets 

    Aichholzer, Oswin; Fabila Monroy, Ruy; Gonzalez Aguilar, Hernan; Hackl, Thomas; Heredia, Marco A.; Huemer, Clemens; Urrutia Galicia, Jorge; Valtr, Pavel; Vogtenhuber, Birgit (2015-08-01)
    Article
    Accés obert
    We consider a variation of the classical Erdos-Szekeres problems on the existence and number of convex k-gons and k-holes (empty k-gons) in a set of n points in the plane. Allowing the k-gons to be non-convex, we show ...
  • Blocking the k-holes of point sets in the plane 

    Cano, Javier; Garcia Olaverri, Alfredo Martin; Hurtado Díaz, Fernando Alfredo; Shakai, Toshinori; Tejel Altarriba, Francisco Javier; Urrutia Galicia, Jorge (2015-09)
    Article
    Accés obert
    Let P be a set of n points in the plane in general position. A subset H of P consisting of k elements that are the vertices of a convex polygon is called a k-hole of P, if there is no element of P in the interior of its ...
  • The diameter of cyclic Kautz digraphs 

    Böhmová, Katerina; Dalfó Simó, Cristina; Huemer, Clemens (2015-11-12)
    Article
    Accés restringit per política de l'editorial
    A prominent problem in Graph Theory is to find extremal graphs or digraphs with restrictions in their diameter, degree and number of vertices. Here we obtain a new family of digraphs with minimal diameter, that is, given ...
  • 3-colorability of pseudo-triangulations 

    Aichholzer, Oswin; Aurenhammer, Franz; Hackl, Thomas; Huemer, Clemens; Pilz, Alexander; Vogtenhuber, Birgit (2015)
    Article
    Accés obert
    Deciding 3-colorability for general plane graphs is known to be an NP-complete problem. However, for certain families of graphs, like triangulations, polynomial time algorithms exist. We consider the family of pseudo-tri ...
  • Quasiperfect domination in trees 

    Cáceres, José; Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Puertas, M. Luz (2015-12-18)
    Article
    Accés restringit per política de l'editorial
    A k–quasiperfect dominating set ( k=1k=1) of a graph G is a vertex subset S such that every vertex not in S is adjacent to at least one and at most k vertices in S. The cardinality of a minimum k–quasiperfect dominating ...
  • Completion and decomposition of hypergraphs into dominating sets of graphs 

    Martí Farré, Jaume; Mora Giné, Mercè; Ruiz Muñoz, José Luis (2015-11)
    Article
    Accés restringit per política de l'editorial
    The collection of the vertex dominating sets of a graph defines a hypergraph on the set of vertices of the graph. However, there are hypergraphs H that are not the collection of the vertex dominating sets of any graph. ...

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