• Aggregated 2D range queries on clustered points 

      Bernardo, Guillermo de; Konow, Bernardo; Navarro, Gonzalo; Brisaboa, Nieves R.; 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. ...
    • 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 ...
    • Exploiting Computation-Friendly Graph Compression Methods for Adjacency-Matrix Multiplication 

      Francisco, Alexandre P.; Gagie, Travis; Ladra, Susana; Navarro, Gonzalo (IEEE Computer Society, 2018-03)
      [Abstract] Computing the product of the (binary) adjacency matrix of a large graph with a real-valued vector is an important operation that lies at the heart of various graph analysis tasks, such as computing PageRank. In ...
    • Extending general compact querieable representations to GIS applications 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Bernardo, Guillermo de; Navarro, Gonzalo; Pedreira, Óscar (Elsevier, 2020-01)
      [Abstract]: The raster model is commonly used for the representation of images in many domains, and is especially useful in Geographic Information Systems (GIS) to store information about continuous variables of the space ...
    • GraCT: A Grammar-based Compressed Index for Trajectory Data 

      Brisaboa, Nieves R.; Gómez-Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Elsevier Ltd, 2019)
      [Abstract]: We introduce a compressed data structure for the storage of free trajectories of moving objects that efficiently supports various spatio-temporal queries. Our structure, dubbed GraCT, stores the absolute positions ...
    • Revisiting Compact RDF Stores Based on k2-Trees 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Bernardo, Guillermo de; Fariña, Antonio (IEEE Xplore, 2020-03)
      [Abstract]: We present a new compact representation to efficiently store and query large RDF datasets in main memory. Our proposal, called BMatrix, is based on the k 2 -tree, a data structure devised to represent binary ...
    • Space-Efficient Representations of Raster Time Series 

      Silva-Coira, Fernando; Paramá, José R.; Bernardo, Guillermo de; Seco, Diego (Elsevier, 2021)
      [Abstract] Raster time series, a.k.a. temporal rasters, are collections of rasters covering the same region at consecutive timestamps. These data have been used in many different applications ranging from weather forecast ...
    • Space/time-efficient RDF stores based on circular suffix sorting 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Bernardo, Guillermo de; Fariña, Antonio; Navarro, Gonzalo (Springer Nature, 2023-03)
      [Abstract]: The resource description framework (RDF) has gained popularity as a format for the standardized publication and exchange of information in the Web of Data. In this paper, we introduce RDFCSA, a compressed ...
    • Tool for SPARQL Querying over Compact RDF Representations 

      Ramos-Vidal, Delfina; Bernardo, Guillermo de (MDPI, 2021)
      [Abstract] We present an architecture for the efficient storing and querying of large RDF datasets. Our approach seeks to store RDF datasets in very little space while offering complete SPARQL functionality. To achieve ...