Now showing items 21-40 of 56

  • De cómo ciertos conjuntos no pueden ser NP-completos 

    Balcázar Navarro, José Luis (Universitat Politècnica de Barcelona. Centre de Càlcul, 1982-09)
    Article
    Open Access
    En este artículo se presenta una visión general a los últimos resultados acontecidos en el área de la estructura de la clase NP-completa y su relación con el problema de si: P=NP o P diferente de NP.
  • Deriving specifications of embeddings in recursive program design 

    Roselló Balanyà, Celestí; Balcázar Navarro, José Luis; Peña Marí, Ricardo (1989)
    External research report
    Open Access
    The design of recursive functions is a well-studied subject. Design methods require a specification to start with, however, when an embedding design is attempted at, it is not clear how the specification of the embedding ...
  • Diameter minimization in networks for SIMD machines 

    Beivide Palacio, Ramon; Balcázar Navarro, José Luis (1985)
    External research report
    Open Access
    We propose an algebraic constructive method which allows to find a certain kind of networks having optimal diameter. These interconnection networks have been proposed for SIMD machines. We compare the results with other ...
  • Empirical results on long-lived renaming algorithms 

    Moral Boadas, Sandra; Balcázar Navarro, José Luis (1997-09)
    External research report
    Open Access
    The Long-lived Renaming problem is an important subject in Distributed Algorithms. The Renaming problem consists in providing processes with new names from a hopefully smaller name space. In the long-lived version, only ...
  • Entailment among probabilistic implications 

    Atserias, Albert; Balcázar Navarro, José Luis (Institute of Electrical and Electronics Engineers (IEEE), 2015)
    Conference report
    Open Access
    We study a natural variant of the implicational fragment of propositional logic. Its formulas are pairs of conjunctions of positive literals, related together by an implicational-like connective, the semantics of this sort ...
  • Examples of CF-bi-inmune and CF-levelable sets in LOGSPACE 

    Balcázar Navarro, José Luis; Díaz Cort, Josep; Gabarró Vallès, Joaquim (1984)
    External research report
    Open Access
    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 ...
  • Frequent sets, sequences, and taxonomies: new, efficient algorithmic proposals 

    Baixeries i Juvillà, Jaume; Casas Garriga, Gemma; Balcázar Navarro, José Luis (2000-12)
    External research report
    Open Access
    We describe efficient algorithmic proposals to approach three fundamental problems in data mining: association rules, episodes in sequences, and generalized association rules over hierarchical taxonomies. The association ...
  • Global optimality in k-means clustering 

    Tîrnauca, Cristina; Gómez Pérez, Domingo; Balcázar Navarro, José Luis; Montaña Arnaiz, José Luis (2018-05-01)
    Article
    Restricted access - publisher's policy
    We study the problem of finding an optimum clustering, a problem known to be NP-hard. Existing literature contains algorithms running in time proportional to the number of points raised to a power that depends on the ...
  • Horn axiomatizations for sequential data 

    Balcázar Navarro, José Luis; Casas Garriga, Gemma (2005-09)
    External research report
    Open Access
    We propose a notion of deterministic association rules for ordered data. We prove that our proposed rules can be formally justified by a purely logical characterization, namely, a natural notion of empirical Horn approximation ...
  • Immunity and simplicity in relativizations of probabilistic complexity classes 

    Balcázar Navarro, José Luis; Russo, David A. (1988-05)
    Article
    Open Access
    The existence of immune and simple sets in relativizations of the probabilistic polynomial time bounded classes is studied. Some techniques previously used to show similar results for relativizations of P and NP are adapted ...
  • Iterator-based algorithms in self-tuning discovery of partial implications 

    Balcázar Navarro, José Luis; García Sáiz, Diego; de la Dehesa, Javier (CEUR Workshop Proceedings, 2012)
    Conference report
    Open Access
    We describe the internal algorithmics of our recent implementation of a closure-based self-tuning associator: yacaree. This system is designed so as not to request the user to specify any threshold. In order to avoid the ...
  • Learnability of Kolmogorov-easy circuit expressions via queries 

    Balcázar Navarro, José Luis; Buhrman, H; Hermo, M (1995-02)
    External research report
    Open Access
    Circuit expressions were introduced to provide a natural link between Computational Learning and certain aspects of Structural Complexity. Upper and lower bounds on the learnability of circuit expressions are known. We ...
  • Learning definite Horn formulas from closure queries 

    Arias Vicente, Marta; Balcázar Navarro, José Luis; Tîrnauca, Cristina (2017-01-07)
    Article
    Open Access
    A definite Horn theory is a set of n-dimensional Boolean vectors whose characteristic function is expressible as a definite Horn formula, that is, as conjunction of definite Horn clauses. The class of definite Horn theories ...
  • Logspace self-reducibility 

    Balcázar Navarro, José Luis (Institute of Electrical and Electronics Engineers (IEEE), 1988)
    Conference report
    Open Access
    A definition of self-reducibility is proposed to deal with logarithmic space complexity classes. A general property derived from the definition is used to prove known results comparing uniform and nonuniform complexity ...
  • Manual de POSTOFF : nueva versión 

    Balcázar Navarro, José Luis (1985)
    External research report
    Open Access
    Un programa adaptador de textos para que el formateador DSR Runoff se haga amiguete de la impresora LA100. Documentación correspondiente a la versión 3.0. Creado por José Luis Balcázar en la F.I.B. durante 1984.
  • Mining educational data for patterns with negations and high confidence boost 

    Balcázar Navarro, José Luis; Tirnauca, Cristina; Zorrilla Pantaleón, Marta Elena (2010)
    Conference report
    Restricted access - publisher's policy
    Association rules constitute a well-known and widely employed data mining technique. We study their applicability in Educational Data Mining. We develop a case study of datasets from that eld: logs of an e-learning ...
  • Mining frequent closed rooted trees 

    Balcázar Navarro, José Luis; Bifet Figuerol, Albert Carles; Lozano Bojados, Antoni (2010-01)
    Article
    Open Access
    Many knowledge representation mechanisms are based on tree-like structures, thus symbolizing the fact that certain pieces of information are related in one sense or another. There exists a well-studied process of closure-based ...
  • New Closure Operators and Lattice Representations for Multivalued Dependencies and Related Expressions 

    Baixeries i Juvillà, Jaume; Balcázar Navarro, José Luis (2005)
    Conference report
    Open Access
    In Database Theory, Multivalued Dependencies are the main tool to define the Fourth Normal Form and, as such, their inference problem has been deeply studied; two related notions appearing in that study are a syntactical ...
  • Nonuniform complexity classes specified by lower and upper bounds 

    Balcázar Navarro, José Luis; Gabarró Vallès, Joaquim (1989-09)
    Article
    Open Access
    We characterize in terms of oracle Turing machines the classes defined by exponential lower bounds on some nonuniform complexity measures. After, we use the same methods to giue a new characterization of classes defined ...
  • Objective novelty of association rules: measuring the confidence boost 

    Balcázar Navarro, José Luis (2010)
    Conference lecture
    Open Access
    On sait bien que la confiance des régles d’association n’est pas vraiment satisfaisant comme mésure d’interêt. Nous proposons, au lieu de la substituer par des autres mésures (soit, en l’employant de façon conjointe a des ...