• An index for moving objects with constant-time access to their compressed trajectories 

      Brisaboa, Nieves R.; Gagie, Travis; Gómez-Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Taylor & Francis, 2021)
      [Abstract]: As the number of vehicles and devices equipped with GPS technology has grown explosively, an urgent need has arisen for time- and space-efficient data structures to represent their trajectories. The most commonly ...
    • Faster compressed quadtrees 

      Bernardo, Guillermo de; Gagie, Travis; Ladra, Susana; Navarro, Gonzalo; Seco, Diego (Elsevier B.V., 2023-02)
      [Abstract]: Real-world point sets tend to be clustered, so using a machine word for each point is wasteful. In this paper we first show how a compact representation of quadtrees using O(1) bits per node can break this bound ...
    • Graph Compression for Adjacency-Matrix Multiplication 

      Francisco, Alexandre P.; Gagie, Travis; Köppl, Dominik; Ladra, Susana; Navarro, Gonzalo (Springer, 2022)
      [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 ...
    • Stronger compact representations of object trajectories 

      Gómez-Brandón, Adrián; Navarro, Gonzalo; R. Paramá, José; Brisaboa, Nieves R.; Gagie, Travis (Taylor & Francis, 2024-02-13)
      [Absctract]: GraCT and ContaCT were the first compressed data structures to represent object trajectories, demonstrating that it was possible to use orders of magnitude less space than classical indexes while staying ...
    • Two-Dimensional Block Trees 

      Brisaboa, Nieves R.; Gagie, Travis; Gómez-Brandón, Adrián; Navarro, Gonzalo (Oxford University Press, 2024-01)
      [Absctract]: The Block Tree is a data structure for representing repetitive sequences in compressed space, which reaches space comparable with that of Lempel–Ziv compression while retaining fast direct access to any position ...