Ara es mostren els items 1-20 de 26

    • A removal lemma for systems of linear equations over finite fields 

      Král, Daniel; Serra Albó, Oriol; Vena Cros, Lluís (2012-01)
      Article
      Accés obert
      We prove a removal lemma for systems of linear equations over finite fields: let X1, . . . , Xm be subsets of the finite field Fq and let A be a (k × m) matrix with coefficients in Fq and rank k; if the linear system Ax = ...
    • An approximate structure theorem for small sumsets 

      Campos, Marcelo; Coulson, Matthew John; Serra Albó, Oriol; Wötzel, Maximilian (Birkhäuser, 2021-08-24)
      Capítol de llibre
      Accés obert
      Let A and B be randomly chosen s-subsets of the first n integers such that their sumset A+B has size at most Ks. We show that asymptotically almost surely A and B are almost fully contained in arithmetic progressions PA ...
    • An Erdös–Fuchs theorem for ordered representation functions 

      Cao Labora, Gonzalo; Rué Perna, Juan José; Spiegel, Christoph (2020-10-28)
      Article
      Accés obert
      Letk=2 be a positive integer. We study concentration results for the ordered representationfunctionsr=k(A, n) = #{(a1= ··· =ak)¿ Ak:a1+···+ak=n}andr<k(A, n) = #{(a1<···<ak)¿ Ak:a1+···+ak=n}for any infinite set ...
    • Applications of Fourier analysis to arithmetic combinatorics 

      Ortega Sánchez Colomer, Miquel (Universitat Politècnica de Catalunya, 2021-02-18)
      Treball Final de Grau
      Accés obert
      Realitzat a/amb:   Lancaster University
      Presentem algunes tècniques elementals de l’anàlisi de Fourier dins la combinatòria aritmètica i les usem per demostrar resultats de caràcter combinatori a conjunts de Sidon grans. Per una banda, demostrem que els conjunts ...
    • Boundary value problems for second order linear difference equations: application to the computation of the inverse of generalized Jacobi matrices 

      Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José (Springer, 2019-07-22)
      Article
      Accés obert
      We have named generalized Jacobi matrices to those that are practically tridiagonal, except for the two final entries and the two first entries of its first andits last row respectively. This class of matrices encompasses ...
    • Correlation among runners and some results on the lonely runner conjecture 

      Perarnau Llobet, Guillem; Serra Albó, Oriol (2016-10-03)
      Article
      Accés obert
      The Lonely Runner Conjecture, posed independently by Wills and by Cusick, states that for any set of runners running along the unit circle with constant different speeds and starting at the same point, there is a time where ...
    • Criptosistema de Lucas 

      Bellot Casanovas, Josep (Universitat Politècnica de Catalunya, 2009-10)
      Projecte Final de Màster Oficial
      Accés obert
      En aquest treball es descriuen exhaustivament les funcions de Lucas i el mètode XTR (mètodes de criptogràfics sobre extessions de cossos finits), i s'analitzen tots els algorismes que s'han publicat fins ara per computar ...
    • Entropy methods for sumset inequalities 

      Espuny Díaz, Alberto (Universitat Politècnica de Catalunya, 2016-07)
      Projecte Final de Màster Oficial
      Accés obert
      In this thesis we present several analogies betweeen sumset inequalities and entropy inequalities. We offer an overview of the different results and techniques that have been developed during the last ten years, starting ...
    • Extremal Sidon sets are Fourier uniform, with applications to partition regularity 

      Ortega Sánchez Colomer, Miquel; Prendiville, Sean (2023-01-01)
      Article
      Accés obert
      Generalising results of Erdos-Freud and Lindström, we prove that the largest Sidon subset of a bounded interval of integers is equidistributed in Bohr neighbourhoods. We establish this by showing that extremal Sidon sets ...
    • Farey graphs as models for complex networks 

      Comellas Padró, Francesc de Paula (2009-08-01)
      Article
      Accés obert
      Farey sequences of irreducible fractions between 0 and 1 can be related to graph constructions known as Farey graphs. These graphs were first introduced by Matula and Kornerup in 1979 and further studied by Colbourn in ...
    • Floquet theory for second order linear homogeneous difference equations 

      Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José (2015-11-05)
      Article
      Accés obert
      In this paper we provide a version of the Floquet’s theorem to be applied to any second order difference equations with quasi-periodic coefficients. To do this we extend to second order linear difference equations with ...
    • Inequality involving sums of diferences of square roots of Fibonacci numbers 

      Díaz Barrero, José Luis (2017-05)
      Article
      Accés restringit per decisió de l'autor
    • On doubling and volume: chains 

      Freiman, Gregory A.; Serra Albó, Oriol (\Institute of Mathematics, Polish Academy of Sciences\, 2018-10-01)
      Article
      Accés obert
      The well-known Freiman–Ruzsa theorem provides a structural description of a set A of integers with |2A|=c|A| as a subset of a d–dimensional arithmetic progression P with |P|=c'|A|, where d and c' depend only on c. The ...
    • On monochromatic solutions of equations in groups 

      Cameron, Peter J.; Cilleruelo, Javier; Serra Albó, Oriol (2006-01-12)
      Article
      Accés obert
      Resum no disponible
    • On Motzkin’s problem in the circle group 

      Candela Pokorna, Pablo; Catalá, Carlos; Rué Perna, Juan José; Serra Albó, Oriol (2021-09-01)
      Article
      Accés obert
      Given a subset D of the interval (0,1), if a Borel set A¿[0,1) contains no pair of elements whose difference modulo 1 is in D, then how large can the Lebesgue measure of A be? This is the analogue in the circle group of a ...
    • Product of primes in arithmetic progressions 

      Ramaré, Olivier; Srivastav, Priyamvad; Serra Albó, Oriol (2020-05-01)
      Article
      Accés obert
      We prove that, for all q=2 and for all invertible residue classes a modulo q, there exists a natural number n=(650q)9 that is congruent to a modulo q and that is the product of exactly three primes, all of which are below ...
    • Semigroups with the Erdös-Turán Property 

      Nesetril, J. (Jaroslav); Serra Albó, Oriol (2006-01)
      Article
      Accés obert
      A set X in a semigroup G has the Erdös-Turán property ET if, for any basis A of X, the representation function rA is ubounded, where rA(x) counts the number of representations of x as a product two elements in A. We ...
    • Symmetries in Steinhaus triangles and in generalized Pascal triangles 

      Brunat Blay, Josep Maria; Maureso Sánchez, Montserrat (2011)
      Article
      Accés restringit per política de l'editorial
      We give explicit formulae for obtaining the binary sequences which produce Steinhaus triangles and generalized Pascal triangles with rotational and dihedral symmetries.
    • Teoría de Floquet para ecuaciones en diferencias lineales de segundo orden y homogéas 

      Jiménez Jiménez, María José (Editorial Universidad de Almería, 2015)
      Comunicació de congrés
      Accés restringit per política de l'editorial
      En este trabajo aportamos una versión del teorema de Floquet aplicable a cualquier ecuación en diferencias lineal de segundo orden con coeficientes casi–periódicos. Obtenemos que este tipo de ecuaciones son equivalentes ...
    • The group inverse of circulant matrices with few parameters 

      Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José; Mitjana Riera, Margarida (2021)
      Comunicació de congrés
      Accés obert
      The need of solving linear systems with circulant matrices occursin many problems related to the periodicity of that problem. This class ofsystem appears in many applications that range from numerical solution ofpartial ...