Now showing items 1-20 of 53

  • A branch-and-price algorithm for the Aperiodic Multi-Period Service Scheduling Problem 

    Fernández Aréizaga, Elena; Kalcsics, Jörg; Núñez del Toro, Alma Cristina (Elsevier, 2017-12-16)
    Article
    Restricted access - publisher's policy
    This paper considers the multi-period service scheduling problem with an aperiodic service policy. In this problem, a set of customers who periodically require service over a finite time horizon is given. To satisfy the ...
  • A connection between Inverse Problems and Nonstandard Analysis 

    Martínez Moraian, Alejandra (Universitat Politècnica de Catalunya, 2018-10)
    Master thesis
    Restricted access - author's decision
    Nonstandard analysis was born in the decade of 1960 an attempt to give a formal context to the Leibniz approach to differential calculus, in particular in order to provide a rigorous foundation to the notions of infinitesimal ...
  • Activities and coefficients of the Tutte polynomial 

    Hakim, Sahar (Universitat Politècnica de Catalunya, 2019-01)
    Master thesis
    Open Access
    Matroids are combinatorial objects that capture abstractly the essence of dependence. The Tutte polynomial, defined for matroids and graphs, has a numerous amount of information about these structures. In this thesis, we ...
  • A fast and efficient algorithm to identify clusters in networks 

    Comellas Padró, Francesc de Paula; Miralles de la Asunción, Alicia (2008-08-02)
    Article
    Open Access
    A characteristic feature of many relevant real life networks, like the WWW, Internet, transportation and communication networks, or even biological and social networks, is their clustering structure. We discuss in this ...
  • A finite version of the Kakeya problem 

    Ball, Simeon Michael; Blokhuis, Aart; Domenzain, Diego (2016-06-02)
    Article
    Open Access
    Let L be a set of lines of an affine space over a field and let S be a set of points with the property that every line of L is incident with at least N points of S. Let D be the set of directions of the lines of L considered ...
  • An algebraic fractal approach to Collatz Conjecture 

    Martín Chabrera, Víctor (Universitat Politècnica de Catalunya, 2019-05)
    Bachelor thesis
    Open Access
    The Collatz conjecture is one of the most easy-to-state unsolved problems in Mathematics today. It states that after a finite number of iterations of the Collatz function, defined by C(n) = n/2 if n is even, and by C(n) = ...
  • An algebraic framework for Diffie-Hellman assumptions 

    Escala Ribas, Alex; Herold, Gottfried; Kiltz, Eike; Ràfols Salvador, Carla; Villar Santos, Jorge Luis (2017-01)
    Article
    Open Access
    We put forward a new algebraic framework to generalize and analyze Di e-Hellman like Decisional Assumptions which allows us to argue about security and applications by considering only algebraic properties. Our D`;k-MDDH ...
  • An analogue of Vosper's theorem for extension fields 

    Bachoc, Christine; Serra Albó, Oriol; Zemor, Gilles (2017-11-01)
    Article
    Open Access
    We are interested in characterising pairs S, T of F-linear subspaces in a field extension L/F such that the linear span ST of the set of products of elements of S and of elements of T has small dimension. Our central result ...
  • An eigenvalue characterization of antipodal distance-regular graphs 

    Fiol Mora, Miquel Àngel (1997-11)
    Article
    Open Access
    Let $\Gamma$ be a regular (connected) graph with $n$ vertices and $d+1$ distinct eigenvalues. As a main result, it is shown that $\Gamma$ is an $r$-antipodal distance-regular graph if and only if the distance graph $\Gamma_d$ ...
  • Bounded expansion in models of webgraphs 

    Gago Álvarez, Silvia; Schlatter, Dirk (2007-10-02)
    Article
    Open Access
    We study the bounded expansion of several models of web graphs. We show that various deterministic graph models for large complex networks have constant bounded expansion.We study two random models of webgraphs, showing ...
  • Bumblebees: a multiagent combinatorial optimization algorithm inspired by social insect behaviour 

    Comellas Padró, Francesc de Paula; Martínez Navarro, Jesús (2009-01-20)
    Conference lecture
    Open Access
    This paper introduces a multiagent optimization algorithm inspired by the collective behavior of social insects. In our method, each agent encodes a possible solution of the problem to solve, and evolves in a way similar ...
  • Characterizations of classes of graphs by forbidden minors 

    Böhmová, Katerina (Universitat Politècnica de Catalunya, 2011)
    Master thesis
    Open Access
    En aquest treball tractem el problema de descriure classes de grafs especificades per un menor prohibit. Concretament, presentem resultats de Wagner que caracteritzen grafs sense K5 o bé K3,3 com a menor. També donem ...
  • Characterizing (l,m)-walk-regularity 

    Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Garriga Valle, Ernest (2009-05)
    Article
    Open Access
    A graph $\G$ with diameter $D$ and $d+1$ distinct eigenvalues is said to be {\it $(\ell,m)$-walk-regular}, for some integers $\ell\in[0,d]$ and $m\in[0,D]$, $\ell\ge m$, if the number of walks of length $i\in [0,\ell]$ ...
  • Classical and modern approaches for Plünnecke-type inequalities 

    Espuny Díaz, Alberto (Universitat Politècnica de Catalunya, 2015-09)
    Bachelor thesis
    Open Access
    The main objective of this thesis is to present and prove Plünnecke's Inequality, a theorem that gives bounds for sumsets in commutative groups. An introduction to the theory of set addition is presented. Three different ...
  • Combinatorial structures to modeling simple games and applications 

    Molinero Albareda, Xavier (American Institute of Physics (AIP), 2017)
    Conference report
    Open Access
    We connect three different topics: combinatorial structures, game theory and chemistry. In particular, we establish the bases to represent some simple games, defined as influence games, and molecules, defined from atoms, ...
  • Combinatorial vs. algebraic characterizations of pseudo-distance-regularity around a set 

    Cámara Vallejo, Marc; Fàbrega Canudas, José; Fiol Mora, Miquel Àngel; Garriga Valle, Ernest (2009-06)
    External research report
    Open Access
    Given a simple connected graph $\Gamma$ and a subset of its vertices $C$, the pseudo-distance-regularity around $C$ generalizes, for not necessarily regular graphs, the notion of completely regular code. Up to now, most ...
  • Corrigendum to"On the limiting distribution of the metric dimension for random forests" [European J. Combin. 49 (2015) 68-89] 

    Mitsche, Dieter; Rué Perna, Juan José (2017-07-22)
    Article
    Open Access
    In the paper ”On the limiting distribution of the metric dimension for random forests” the metric dimension ß(G) of sparse G(n, p) with p = c/n and c < 1 was studied (Theorem 1.2). In the proof of this theorem, for the ...
  • Cuadrados latinos y grafos de Moore 

    Acero Sistach, Lluís (Universitat Politècnica de Catalunya, 2004-07)
    Minor thesis
    Open Access
    Bajo el título Cuadrados latinos y grafos de Moore se esconden dos campos de la matemática bastante peculiares. Por un lado los cuadrados latinos, tan viejos casi como la antigua Grecia y a su vez tan poco estudiados que ...
  • Del teorema de los 4 colores a la gravedad cuántica: enumeración de mapas 

    Rué Perna, Juan José (Real Sociedad Matemática Española, 2011-05-03)
    Article
    Open Access
    Es más que habitual que cuestiones elementales no tengan una respuesta sencilla. Esto ocurre con el enigma con el que iniciaremos esta aventura hacia la combinatoria de los mapas. Deseamos pintar los distintos términos ...
  • Digraphs with walks of equal length between vertices 

    Fiol Mora, Miquel Àngel; Alegre, Ignasi; Andrés Yebra, José Luís; Fàbrega Canudas, José (1984)
    Conference report
    Open Access