Ara es mostren els items 32-51 de 94

    • Chromatic number in random scaled sector graphs 

      Díaz Cort, Josep; Sanwalani, Vishal; Serna Iglesias, María José; Spirakis, Paul George (2004-04)
      Report de recerca
      Accés obert
      In this paper, we introduce a new model of random graph that we call random sector graph. This model aims to provide a tool for studying communication problems in networks of sensors using laser communication such as ...
    • Classes of bounded nondeterminism 

      Díaz Cort, Josep; Torán Romero, Jacobo (1988)
      Report de recerca
      Accés obert
      We study certain language classes located between P and N P that are defined by polynomial time machines with a bounded amount of nondeterminism. We observe that these classes have complete problems and find a characterization ...
    • Combinatòria i complexitat algorísmica 

      Berenguer Villaseca, Xavier; Casas, Rafael; Díaz Cort, Josep; Sobrevilla Frisón, Pilar (Universitat Politècnica de Barcelona, 1980-12)
      Text en actes de congrés
      Accés obert
    • Communication tree problems 

      Álvarez Faura, M. del Carme; Cases Muñoz, Rafel; Díaz Cort, Josep; Petit Silvestre, Jordi; Serna Iglesias, María José (2001-03)
      Report de recerca
      Accés obert
      In this paper, we consider random communication requirements and several cost measures for a particular model of tree routing on a complete network. First we show that a random tree does not give any approximation. Then ...
    • Complejidad de problemas combinatorios 

      Díaz Cort, Josep (Universitat Politècnica de Barcelona. Centre de Càlcul, 1978-03)
      Article
      Accés obert
      Un gran número de problemas entre los que se encuentran problemas tan conocidos como el del viajante de comercio, o el problema isoperimétrico, se muéstran como equivalentes en el sentido de que si uno de ellos admite una ...
    • Complexity issues on bounded restrictive H-coloring 

      Serna Iglesias, María José; Díaz Cort, Josep; Thilikos Touloupas, Dimitrios (2004-04)
      Report de recerca
      Accés obert
      We consider the restriction of the H-coloring problem where we are looking for homomorphisms were the number of preimages of certain vertices of H is bounded by some fixed constant. We consider the decision and the ...
    • Complexity of metric dimension on planar graphs 

      Díaz Cort, Josep; Pottonen, Ollie; Serna Iglesias, María José; van Leeuwen, Erik Jan (2017-04-03)
      Article
      Accés obert
      The metric dimension of a graph G is the size of a smallest subset L ¿ V (G) such that for any x, y ¿ V (G) with x =/ y there is a z ¿ L such that the graph distance between x and z differs from the graph distance between ...
    • Computation of bisection width for random d-regular graphs 

      Díaz Cort, Josep; Serna Iglesias, María José; Wormald, Nick (2003-07)
      Report de recerca
      Accés obert
      In this paper we describe a randomized greedy algorithm for obtaining bisections of graphs. Analysis of the algorithm's performance on random d-regular graphs yields asymptotically almost sure upper bounds on the bisection ...
    • Continuous monitoring in the dynamic sensor field model 

      Álvarez Faura, M. del Carme; Díaz Cort, Josep; Dieter Wilhelm, Mitsche; Serna Iglesias, María José (2011-05)
      Report de recerca
      Accés obert
      In this work we consider the problem of continuously monitoring a collection of data sets produced by sensors placed on moving or static targets. We propose a modification of the static sensor field model (SSSF) [2] to ...
    • Convergence theorems for some layout measures on random lattice and random geometric graphs 

      Díaz Cort, Josep; Penrose, Matthew; Petit Silvestre, Jordi; Serna Iglesias, María José (1999-04)
      Report de recerca
      Accés obert
      This work deals with convergence theorems and bounds on the cost of several layout measures for lattice graphs, random lattice graphs and sparse random geometric graphs. For full square lattices, we give optimal layouts ...
    • Counting H-colorings of partial k-trees 

      Díaz Cort, Josep; Serna Iglesias, María José; Thilikos Touloupas, Dimitrios (2000-11)
      Report de recerca
      Accés obert
      The problem of counting all H-colorings of a graph G of n vertices is considered. While the problem is, in general #P-complete, we give linear time algorithms that solve the main variants of this problem when the input ...
    • Counting list h-colorings and variants 

      Díaz Cort, Josep; Serna Iglesias, María José; Thilikos Touloupas, Dimitrios (2001-05)
      Report de recerca
      Accés obert
      We study the counting versions of several variants of the H-coloring problem. The complexity of the H-coloring problem is described by a dichotomy theorem that classifies the problem according to the the topology of H ...
    • Efficient algorithms for parameterized H-colorings 

      Díaz Cort, Josep; Serna Iglesias, María José; Thilikos Touloupas, Dimitrios (2005-12)
      Report de recerca
      Accés obert
      We study the fixed parameter tractability of the restrictive $H$-coloring and the restrictive list $H$-coloring problems, introduced in~cite{DST01b}. The parameterizations are defined by fixing the number of pre-images of ...
    • Efficient parallel algorithms for some tree layout problems 

      Díaz Cort, Josep; Gibbons, Alan M.; Pantziou, Grammati; Serna Iglesias, María José; Spirakis, Paul George; Torán Romero, Jacobo (1992)
      Report de recerca
      Accés obert
      The minimum cut and minimum sum linear arrangement problems usually occur in solving wiring problems and have a lot in common with job sequencing questions. Both problems are NP-complete for general graphs and P for trees. ...
    • El problema de l’ordenació no linial òptima és np-complet 

      Díaz Cort, Josep (Universitat Politècnica de Barcelona. Centre de Càlcul, 1978-12)
      Article
      Accés obert
      L'article descriu la reducció del Problema de Tall màxim Simple al Problema de l'Ordenació no Lineal Òptima, la qual cosa implica la pertinença d'aquest últim a la classe NP-Complet.
    • ESQUEMES ALGORÍSMICS (Examen 1r quadrim.) 

      Díaz Cort, Josep (Universitat Politècnica de Catalunya, 1999-01-08)
      Examen
      Accés restringit a la comunitat UPC
    • ESQUEMES ALGORÍSMICS (Examen 2n quadrim.) 

      Díaz Cort, Josep (Universitat Politècnica de Catalunya, 2001-06-30)
      Examen
      Accés restringit a la comunitat UPC
    • Examples of CF-bi-inmune and CF-levelable sets in LOGSPACE 

      Balcázar Navarro, José Luis; Díaz Cort, Josep; Gabarró Vallès, Joaquim (1984)
      Report de recerca
      Accés obert
      We find sets in the class LOGSPACE (on-line) that do not have good respectively approximations by context-free languages. For that we introduce the languages CF-bi-inmune and CF-levelable. We prove the results by defining ...
    • Faulty random geometric networks 

      Díaz Cort, Josep; Petit Silvestre, Jordi; Serna Iglesias, María José (2000-10)
      Report de recerca
      Accés obert
      In this paper we analyze the computational power of random geometric networks in the presence of random (edge or node) faults considering several important network parameters. We first analyze how to emulate an original ...
    • Génesis y evolución de la informática teórica 

      Díaz Cort, Josep (1984)
      Report de recerca
      Accés obert