Enviaments recents

  • Stabbing segments with rectilinear objects 

    Claverol Aguas, Mercè; Garijo Royo, Delia; Korman, Matias; Seara Ojea, Carlos; Silveira, Rodrigo Ignacio (2017-09-15)
    Article
    Accés obert
    Given a set S of n line segments in the plane, we say that a region R¿R2 is a stabber for S if R contains exactly one endpoint of each segment of S. In this paper we provide optimal or near-optimal algorithms for ...
  • On perfect and quasiperfect dominations in graphs 

    Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Cáceres, José; Puertas, M. Luz (2017-02-27)
    Article
    Accés obert
    A subset S ¿ V in a graph G = ( V , E ) is a k -quasiperfect dominating set (for k = 1) if 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 ...
  • Stabbing circles for sets of segments in the plane 

    Claverol Aguas, Mercè; Khramtcova, Elena; Papadopoulou, Evanthia; Saumell, Maria; Seara Ojea, Carlos (2017-03-13)
    Article
    Accés obert
    Stabbing a set S of n segments in the plane by a line is a well-known problem. In this paper we consider the variation where the stabbing object is a circle instead of a line. We show that the problem is tightly connected ...
  • General properties of c-circulant digraphs 

    Mora Giné, Mercè; Serra Albó, Oriol; Fiol Mora, Miquel Àngel (1988)
    Article
    Accés obert
    A digraph is said to be a c-circulant if its adjacency matrix is c-circulant. This paper deals with general properties of this family of digraphs, as isomorphisms, regularity, strong connectivity, diameter and the relation ...
  • Production matrices for geometric graphs 

    Huemer, Clemens; Pilz, Alexander; Seara Ojea, Carlos; Silveira, Rodrigo Ignacio (2016)
    Article
    Accés restringit per política de l'editorial
    We present production matrices for non-crossing geometric graphs on point sets in convex position, which allow us to derive formulas for the numbers of such graphs. Several known identities for Catalan numbers, Ballot ...
  • New results on stabbing segments with a polygon 

    Díaz Bañez, José Miguel; Korman Cozzetti, Matías; Pérez Lantero, Pablo; Pilz, Alexander; Seara Ojea, Carlos; Silveira, Rodrigo Ignacio (2015-01-01)
    Article
    Accés obert
    We consider a natural variation of the concept of stabbing a set of segments with a simple polygon: a segment s is stabbed by a simple polygon P if at least one endpoint of s is contained in P, and a segment set S is stabbed ...
  • Adjacency-preserving spatial treemaps 

    Buchin, Kevin; Eppstein, David; Löffler, Maarten; Nöllenburg, Martin; Silveira, Rodrigo Ignacio (2016)
    Article
    Accés obert
    Rectangular layouts, subdivisions of an outer rectangle into smaller rectangles, have many applications in visualizing spatial information, for instance in rectangular cartograms in which the rectangles represent geographic ...
  • Widening the analysis of Energy Return On Investment (EROI) in agroecosystems: A proposal to study socio-ecological transitions to industrialized farm systems (the Vallès County, Catalonia, c.1860 and 1999) 

    Galán, E.; Padró, R.; Marco, I.; Tello Aragay, Enric; Cunfer, G.; Guzmán, G. I.; González de Molina, M.; Krausmann, F.; Gingrich, S.; Sacristán Adinolfi, Vera; Moreno-Delgado, D. (2016)
    Article
    Accés restringit per política de l'editorial
    Energy balances of farm systems have overlooked the role of energy flows that remain within agro-ecosystems. Yet, such internal flows fulfil important socio-ecological functions, including maintenance of farmers themselves ...
  • Computing the canonical representation of constructible sets 

    Brunat Blay, Josep Maria; Montes Lozano, Antonio (2016-03-08)
    Article
    Accés obert
    Constructible sets are needed in many algorithms of Computer Algebra, particularly in the GröbnerCover and other algorithms for parametric polynomial systems. In this paper we review the canonical form ofconstructible sets ...
  • 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 ...

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