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    • Algorítmica per a paral·lelisme massiu : introducció 

      Díaz Cort, Josep; Serna Iglesias, María José (Edicions UPC, 1999)
      Llibre
      Accés restringit a la comunitat UPC
      Aquest llibre és una introducció al disseny d’algorismes paral·lels per a màquines síncrones. Als capítols 1-5 es presenten els conceptes bàsics del disseny d’algorismes per a xarxes d’interconexió: vectors, meshes, meshes ...

    • Algunes consideracions teòriques al problema de la construcció d’horaris (comunicació breu) 

      Berenguer, Xavier; Díaz Cort, Josep (Universitat Politècnica de Barcelona. Centre de Càlcul, 1980-03)
      Article
      Accés obert
      Corominas i Roselló varen presentar una visió general dels algorismes per a resoldre el problema de la construcció d'horaris en centres escolars. En aquesta comunicació es pretén completar aquest treball amb una revisió ...

    • An optimal parallel algorithm for learning DFA 

      Balcázar Navarro, José Luis; Díaz Cort, Josep; Gavaldà Mestre, Ricard; Watanabe, O. (Universitat Politècnica de Catalunya. Departament de Llenguatges i Sistemes Informàtics, 1993-01-01)
      Report de recerca
      Accés obert
      In 1987, D. Angluin presented an algorithm that exactly learns regular languages represented by deterministic finite automata (dfa) from Membership and Equivalence queries. Furthermore, the algorithm is feasible in the ...

    • Approximating layout problems on geometric random graphs 

      Díaz Cort, Josep; Penrose, Mathew D.; Petit Silvestre, Jordi; Serna Iglesias, María José (1998-10-13)
      Report de recerca
      Accés obert
      We show two simple algorithms that, with high probability, approximate within a constant several layout problems for geometric random graphs drawn from the Gn(r) model r_cv(log¿¿n/n¿ ) for any constant c = 6. The layout ...

    • Approximating layout problems on random sparse graphs 

      Díaz Cort, Josep; Petit Silvestre, Jordi; Serna Iglesias, María José; Trevisan, Marco (1998-07)
      Report de recerca
      Accés obert
      We show that, with high probability, several layout problems are approximable within a constant for random graphs drawn from the standard Gnp model with p=c/n for some constant c. Our results establish that, in fact, ...

    • Approximating the permanent is in RNC 

      Díaz Cort, Josep; Serna Iglesias, María José; Spirakis, Paul George (1995-04)
      Report de recerca
      Accés obert
      In this work we look into the parallelization (in the NC sense) of the Markov Chain approach to almost random generation, as described by Sinclair (1993). We give a RNC almost uniform generator for perfect matchings in ...

    • Average case analysis of Robinson's unification algorithm with two different variables 

      Cases Muñoz, Rafael; Díaz Cort, Josep; Steyaert, Jean-Marc (1988)
      Report de recerca
      Accés obert
      We compute the average complexity of Robinson's unification algorithm on the case of binary functions with two variables. When restricting the input to unifiable instances, the resulting complexity is linear on the size ...

    • Average-case analysis on simple families of trees using a balanced probabilistic model 

      Cases Muñoz, Rafel; Díaz Cort, Josep; Martínez Parra, Conrado (1991-02-20)
      Report de recerca
      Accés obert
      In this paper we study a balanced probability model defined over simple families of trees, which from the point of doing statistics on trees, behave in quite a different way from the uniform distribution. Using the new ...

    • Bisection of random cubic graphs 

      Díaz Cort, Josep; Do, Norman; Serna Iglesias, María José; Wormald, Nick (2002-05)
      Report de recerca
      Accés obert
      In this paper we present two randomized algorithms to compute the bisection width of random cubic graphs with n vertices, giving an asymptotic upper bound for the bisection width respectively of 0.174039n and 0.174501n. ...

    • Bounds on the bisection width for random d-regular graphs 

      Díaz Cort, Josep; Serna Iglesias, María José; Wormald, Nick (2004-04)
      Report de recerca
      Accés obert
      In this paper we provide an explicit way to compute asymptotically almost sure upper bounds on the bisection width of random d-regular graphs, for any value of d. The upper bounds are obtained from the analysis of the ...

    • Bounds on the max and min bisection of random cubic and 4-regular graphs 

      Díaz Cort, Josep; Do, Norman; Serna Iglesias, María José; Wormald, Nick (2002-12)
      Report de recerca
      Accés obert
      In this paper we present simple randomized algorithms to bisect cubic and 4-regular graphs. These algorithms produce bisections of size asymptotically at most 0.17404n for typical random cubic n-vertex graphs, and ...

    • 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 ...