Now showing items 1-20 of 56

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

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 $\Gamma_d$ ...
• #### Anticyclotomic p-adic L-functions and the exceptional zero phenomenon ﻿

(2019-08-15)
Article
Open Access
Let A be a modular elliptic curve over a totally real field F, and let E/F be a totally imaginary quadratic extension. In the event of exceptional zero phenomenon, we prove a formula for the derivative of the multivariable ...
• #### Approximation schemes for randomly sampling colorings ﻿

(Universitat Politècnica de Catalunya, 2019-10)
Master thesis
Open Access
Graph colouring is arguably one of the most important issues in Graph Theory. However, many of the questions that arise in the area such as the chromatic number problem or counting the number of proper colorings of a graph ...
• #### Bounded expansion in models of webgraphs ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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] ﻿

(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 ...