Now showing items 1-8 of 8

    • A correction on Shiloach's algorithm for minimum linear arrangement of trees 

      Esteban Ángeles, Juan Luis; Ferrer Cancho, Ramon (2017-06-29)
      Article
      Open Access
      More than 30 years ago, Shiloach published an algorithm to solve the minimum linear arrangement problem for undirected trees. Here we fix a small error in the original version of the algorithm and discuss its effect on ...
    • Are crossing dependencies really scarce? 

      Ferrer Cancho, Ramon; Gómez Rodríguez, Carlos; Esteban Ángeles, Juan Luis (2018-03-01)
      Article
      Open Access
      The syntactic structure of a sentence can be modelled as a tree, where vertices correspond to words and edges indicate syntactic dependencies. It has been claimed recurrently that the number of edge crossings in real ...
    • Automatic detection of at-most-one and exactly-one relations for improved SAT encodings of pseudo-boolean constraints 

      Ansótegui Gil, Carlos; Bofill Arasa, Miquel; Coll Caballero, Jordi; Dang, Nguyen; Esteban Ángeles, Juan Luis; Miguel, Ian; Nightingale, Peter; Salamon, András Z.; Suy Franch, Josep; Villaret Auselle, Mateu (Springer, 2019)
      Conference report
      Open Access
      Pseudo-Boolean (PB) constraints often have a critical role in constraint satisfaction and optimisation problems. Encoding PB constraints to SAT has proven to be an efficient approach in many applications, however care must ...
    • Bounds of the sum of edge lengths in linear arrangements of trees 

      Ferrer Cancho, Ramon; Gómez Rodríguez, Carlos; Esteban Ángeles, Juan Luis (Institute of Physics (IOP), 2021-02-11)
      Article
      Restricted access - publisher's policy
      A fundamental problem in network science is the normalization of the topological or physical distance between vertices, which requires understanding the range of variation of the unnormalized distances. Here we investigate ...
    • Complexity measures for resolution 

      Esteban Ángeles, Juan Luis (Universitat Politècnica de Catalunya, 2003-12-15)
      Doctoral thesis
      Open Access
      Esta obra es una contribución al campo de la Complejidad de la Demostración, que estudia la complejidad de los sistemas de demostración en términos de los recursos necesarios para demostrar o refutar fórmulas proposicionales. ...
    • Exponential separation between tree-like and dag-like Cutting Planes proof systems 

      Bonet Carbonell, M. Luisa; Esteban Ángeles, Juan Luis; Galesi, Nicola; Johannsen, Jan (1997-12)
      External research report
      Open Access
      We prove an exponential lower bound for tree-like Cutting Planes refutations of a set of clauses which has polynomial size resolution refutations. This implies an exponential separation between tree-like and dag-like ...
    • On the complexity of resolution with bounded conjunctions 

      Esteban Ángeles, Juan Luis; Galesi, Nicola; Messner, Jochen (2003-06)
      External research report
      Open Access
      We analyze size and space complexity of Res(k), a family of propositional proof systems introduced by Kraj which extend Resolution by allowing disjunctions of conjunctions of up to 1$ literals. We show that the ...
    • The scaling of the minimum sum of edge lengths in uniformly random trees 

      Esteban Ángeles, Juan Luis; Ferrer Cancho, Ramon; Gómez Rodríguez, Carlos (Institute of Physics (IOP), 2016-06-21)
      Article
      Open Access
      The minimum linear arrangement problem on a network consists of finding the minimum sum of edge lengths that can be achieved when the vertices are arranged linearly. Although there are algorithms to solve this problem on ...