Exploració per autor "Díaz Cort, Josep"
Ara es mostren els items 44-63 de 94
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Efficient algorithms for parameterized H-colorings
Díaz Cort, Josep; Serna Iglesias, María José; Thilikos Touloupas, Dimitrios (2005-12)
Report de recerca
Accés obertWe 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 obertThe 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 obertL'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 obertWe 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 obertIn 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 -
Graph layout problems
Díaz Cort, Josep (1992)
Report de recerca
Accés obertIn this paper we survey the recent results and open questions about some graph layout problems. -
(H,C,K)-colorings: fast, easy, and hard cases
Díaz Cort, Josep; Serna Iglesias, María José; Thilikos Touloupas, Dimitrios (2001-05)
Report de recerca
Accés obertWe define a variant of the H-coloring problem by fixing the number of preimages of a subset C of the vertices of H, thus allowing parameterization. We provide sufficient conditions to guarantee that the problem can be ... -
H-colorings of large degree graphs
Díaz Cort, Josep; Nesetril, Jaroslav; Serna Iglesias, María José; Thilikos, Dimitrios (2000-04)
Report de recerca
Accés obertWe consider the H-coloring problem on graphs with vertices of large degree. We prove that for H an odd cycle, the problem belongs to P. We also study the phase transition of the problem, for an infinite family of ... -
Heuristics for the MinLA problem: an empirical and theoretical analysis
Díaz Cort, Josep; Petit Silvestre, Jordi; Serna Iglesias, María José; Spirakis, Paul George (1998-07)
Report de recerca
Accés obertThis paper considers the development and the analysis of Local Search heuristics to approximate the Minimum Linear Arrangement problem. First of all, we present a new heuristic that we call SS+SA based on the combination ... -
Heuristics for the MinLA problem: some theoretical and empirical considerations
Díaz Cort, Josep; Petit Silvestre, Jordi; Spirakis, Paul George; Serna Iglesias, María José (1998-03)
Report de recerca
Accés obertThis paper deals with some aspects on finding good solutions for the Minimum Linear Arrangement problem (MinLA). We consider some random type of sparse graphs, for which it is possible to obtain trivial constant ... -
High level communication functionalities for wireless sensor networks
Álvarez Faura, M. del Carme; Díaz Cort, Josep; Petit Silvestre, Jordi; Rolim, José; Serna Iglesias, María José (2004-11)
Report de recerca
Accés obertIn this work we propose a way to establish a reliable and efficient high level communication system in a randomly deployed network of sensors equipped with directional antennas. This high level communication system will ... -
Improved reconstruction of random geometric graphs
Dani, Varsha; Díaz Cort, Josep; Hayes, Thomas P.; Moore, Cristopher (Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2022)
Text en actes de congrés
Accés obertEmbedding graphs in a geographical or latent space, i.e. inferring locations for vertices in Euclidean space or on a smooth manifold or submanifold, is a common task in network analysis, statistical inference, and graph ... -
Intervalizing colored graphs is NP-complete for caterpilars with hair length 2
Álvarez Faura, M. del Carme; Díaz Cort, Josep; Serna Iglesias, María José (1998-02)
Report de recerca
Accés obertThe problem of Intervalizing Colored Graphs has received a lot of attention due to their use as a model for DNA physical mapping with ambiguous data. If k is the number of colors, the problem is known to be NP-Complete ... -
Lazlo Lovász i Avi Widergson: premis Abel 2021
Rué Perna, Juan José; Díaz Cort, Josep; Guàrdia Rubies, Jordi; Atserias, Albert; Serra Albó, Oriol (Societat Catalana de Matemàtiques (SCM), 2021-12-14)
Article
Accés obertEl dia 17 de març l’Acadèmia de Ciències Noruega va anunciar que el Premi Abel 2021 s’atorgava a Laszló Lovász i Avi Widgerson per, segons es llegeix de la laudatio del premi, “. . . les seves contribucions fonamentals a ... -
Learning random points from geometric graphs or orderings
Díaz Cort, Josep; Mcdiarmid, Colin; Mitsche, Dieter (2020-09)
Article
Accés obertLet Xv for v∈V be a family of n iid uniform points in the square (Formula presented.). Suppose first that we are given the random geometric graph (Formula presented.), where vertices u and v are adjacent when the Euclidean ... -
Linear and non-linear systems: a survey
Díaz Cort, Josep; Serna Iglesias, María José; Spirakis, Paul George (1997-12)
Report de recerca
Accés obertIn this paper we present the research that has been done with Linear Dynamical Systems to generate almost uniformly elements from a given set, and thus approximate some hard counting problems. We also indicate how non-linear ... -
Linear orderings of random geometric graphs (extended abstract)
Díaz Cort, Josep; Penrose, Matthew; Petit Silvestre, Jordi; Serna Iglesias, María José (1999-04)
Report de recerca
Accés obertIn random geometric graphs, vertices are randomly distributed on [0,1]^2 and pairs of vertices are connected by edges whenever they are sufficiently close together. Layout problems seek a linear ordering of the vertices ...