Browsing by Subject "Combinacions (Matemàtica)"
Now showing items 120 of 100

A branchandprice algorithm for the Aperiodic MultiPeriod Service Scheduling Problem
(Elsevier, 20171216)
Article
Open AccessThis paper considers the multiperiod 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, 201810)
Master thesis
Restricted access  author's decisionNonstandard 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 ... 
A fast and efficient algorithm to identify clusters in networks
(20080802)
Article
Open AccessA 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
(20160602)
Article
Open AccessLet 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 ... 
A general method to obtain the spectrum and local spectra of a graph from its regular partitions
(20200712)
Article
Open AccessIt is well known that, in general, part of the spectrum of a graph can be obtained from the adjacency matrix of its quotient graph given by a regular partition. In this paper, a method that gives all the spectrum, and also ... 
A unified formal framework for factorial and probabilistic topic modelling
(Multidisciplinary Digital Publishing Institute (MDPI), 20231021)
Article
Open AccessTopic modelling has become a highly popular technique for extracting knowledge from texts. It encompasses various method families, including Factorial methods, Probabilistic methods, and Natural Language Processing methods. ... 
Activities and coefficients of the Tutte polynomial
(Universitat Politècnica de Catalunya, 201901)
Master thesis
Open AccessMatroids 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 ... 
Additive volume of sets contained in few arithmetic progressions
(De Gruyter, 20190306)
Article
Open AccessA conjecture of Freiman gives an exact formula for the largest volume of a finite set A of integers with given cardinality k=A and doubling T=2A. The formula is known to hold when T=3k4, for some small range over 3k4 ... 
An algebraic fractal approach to Collatz Conjecture
(Universitat Politècnica de Catalunya, 201905)
Bachelor thesis
Open AccessThe Collatz conjecture is one of the most easytostate 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 DiffieHellman assumptions
(201701)
Article
Open AccessWe put forward a new algebraic framework to generalize and analyze Di eHellman like Decisional Assumptions which allows us to argue about security and applications by considering only algebraic properties. Our D`;kMDDH ... 
An analogue of Vosper's theorem for extension fields
(20171101)
Article
Open AccessWe are interested in characterising pairs S, T of Flinear 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 distanceregular graphs
(199711)
Article
Open AccessLet $\Gamma$ 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 distanceregular graph if and only if the distance graph $\Gamma_d$ ... 
Anticyclotomic padic Lfunctions and the exceptional zero phenomenon
(20190815)
Article
Open AccessLet 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, 201910)
Master thesis
Open AccessGraph 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 ... 
Asymptotics in the schema of simple varieties of trees
(Universitat Politècnica de Catalunya, 202205)
Master thesis
Open AccessWe study the functional equation y(x) = xA(y(x)) satisfied by the generating functions in the schema of simple varieties of trees. The radii of convergence r, R of y, A respectively satisfy y(r) <= R. In the subcritical ... 
Big Ramsey degrees of 3uniform hypergraphs
(2019)
Conference report
Open AccessGiven a countably infinite hypergraph $\mathcal R$ and a finite hypergraph $\mathcal A$, the \emph{big Ramsey degree} of $\mathcal A$ in $\mathcal R$ isthe least number $L$ such that, for every finite $k$ and every ... 
Bounded expansion in models of webgraphs
(20071002)
Article
Open AccessWe 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
(20090120)
Conference lecture
Open AccessThis 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 ... 
Center of maximumsum matchings of bichromatic points
(Elsevier, 20240301)
Article
Restricted access  publisher's policyLet R and B be two point sets in the plane with . Let be a perfect matching that matches points of R with points of B and maximizes , the total Euclidean distance of the matched pairs. In this paper, we prove that there ... 
Characterizations of classes of graphs by forbidden minors
(Universitat Politècnica de Catalunya, 2011)
Master thesis
Open AccessEn 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 ...