Now showing items 1-15 of 15

    • Aggregated 2D range queries on clustered points 

      Bernardo Roca, Guillermo de; Konow, Bernardo; Navarro, Gonzalo; Rodríguez Brisaboa, Nieves; Seco, Diego (Elsevier Ltd, 2016-09)
      [Abstract] Efficient processing of aggregated range queries on two-dimensional grids is a common requirement in information retrieval and data mining systems, for example in Geographic Information Systems and OLAP cubes. ...
    • Efficient and Compact Representations of Some Non-canonical Prefix-Free Codes 

      Fariña, Antonio; Gagie, Travis; Manzini, Giovanni; Navarro, Gonzalo; Ordóñez, Alberto (Springer, 2016-09-21)
      [Abstract] For many kinds of prefix-free codes there are efficient and compact alternatives to the traditional tree-based representation. Since these put the codes into canonical form, however, they can only be used when ...
    • Compact Trip Representation over Networks 

      Brisaboa, Nieves R.; Fariña, Antonio; Galaktionov, Daniil; Rodríguez, M. Andrea (Springer, 2016-09-21)
      [Abstract] We present a new Compact Trip Representation ( CTRCTR ) that allows us to manage users’ trips (moving objects) over networks. These could be public transportation networks (buses, subway, trains, and so on) where ...
    • GraCT: A Grammar Based Compressed Representation of Trajectories 

      Brisaboa, Nieves R.; Gómez Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Springer, 2016-09-21)
      [Abstract] We present a compressed data structure to store free trajectories of moving objects (ships over the sea, for example) allowing spatio-temporal queries. Our method, GraCT, uses a k2k2 -tree to store the absolute ...
    • Efficient Representation of Multidimensional Data over Hierarchical Domains 

      Brisaboa, Nieves R.; Cerdeira Pena, Ana Belén; López López, Narciso; Navarro, Gonzalo; Penabad, Miguel R.; Silva-Coira, Fernando (Springer, 2016-09-21)
      [Abstract] We consider the problem of representing multidimensional data where the domain of each dimension is organized hierarchically, and the queries require summary information at a different node in the hierarchy of ...
    • Parallel construction of wavelet trees on multicore architectures 

      Fuentes Sepúlveda, José; Elejalde, Erick; Ferres, Leo; Seco, Diego (Springer U K, 2016-10-05)
      [Abstract] The wavelet tree has become a very useful data structure to efficiently represent and query large volumes of data in many different domains, from bioinformatics to geographic information systems. One problem ...
    • Grammar compressed sequences with rank/select support 

      Ordóñez, Alberto; Navarro, Gonzalo; Brisaboa, Nieves R. (Elsevier BV, 2016-10-14)
      [Abstract] Sequence representations supporting not only direct access to their symbols, but also rank/select operations, are a fundamental building block in many compressed data structures. Several recent applications need ...
    • A succinct data structure for self-indexing ternary relations 

      Álvarez García, Sandra; De Bernardo Roca, Guillermo; Rodríguez Brisaboa, Nieves; Navarro, Gonzalo (Elsevier BV, 2016-10-27)
      [Abstract] The representation of binary relations has been intensively studied and many different theoretical and practical representations have been proposed to answer the usual queries in multiple domains. However, ternary ...
    • Universal indexes for highly repetitive document collections 

      Claude, Francisco; Fariña, Antonio; Martínez Prieto, Miguel A.; Navarro, Gonzalo (Elsevier Ltd, 2016-11)
      [Abstract] Indexing highly repetitive collections has become a relevant problem with the emergence of large repositories of versioned documents, among other applications. These collections may reach huge sizes, but are ...
    • A new method to index and store spatio-temporal data 

      Bernardo Roca, Guillermo de; Casares, Ramón; Gómez Brandón, Adrián; Paramá, José R. (2016-11-16)
      [Abstract] We propose a data structure that stores, in a compressed way, object trajectories, which at the same time, allow to efficiently response queries without the need to decompress the data. We use a data structure, ...
    • Navigational Rule Derivation: An algorithm to determine the effect of traffic signs on road networks 

      Galaktionov, Daniil; Luaces, Miguel R.; Places, Ángeles S. (2016-11-17)
      [Abstract] In this paper we present an algorithm to build a road network map enriched with traffic rules such as one-way streets and forbidden turns, based on the interpretation of already detected and classified traffic ...
    • Design of Mutation Operators for Testing Geographic Information Systems 

      Alvarado, Suilen H. (M D P I AG, 2019-08-06)
      [Abstract] In this article, we propose the definition of specific mutation operators for testing Geographic Information Systems. We describe the process for applying the operators and generating mutants, and present a case ...
    • Energy Consumption in Compact Integer Vectors: A Study Case 

      Fuentes Sepúlveda, José; Ladra, Susana (Institute of Electrical and Electronics Engineers, 2019-10-25)
      [Abstract] In the field of algorithms and data structures analysis and design, most of the researchers focus only on the space/time trade-off, and little attention has been paid to energy consumption. Moreover, most of the ...
    • Improved Compressed String Dictionaries 

      Brisaboa, Nieves R.; Cerdeira Pena, Ana Belén; De Bernardo Roca, Guillermo; Navarro, Gonzalo (ACM, 2019-11-03)
      [Abstract] We introduce a new family of compressed data structures to efficiently store and query large string dictionaries in main memory. Our main technique is a combination of hierarchical Front-coding with ideas from ...
    • Efficient processing of raster and vector data 

      Silva-Coira, Fernando; Paramá, José R.; Ladra, Susana; López, Juan R.; Gutiérrez, Gilberto (Public Library of Science, 2020-01-10)
      [Abstract] In this work, we propose a framework to store and manage spatial data, which includes new efficient algorithms to perform operations accepting as input a raster dataset and a vector dataset. More concretely, we ...