Now showing items 1-20 of 21

    • Axiomàtica dels nombres reals 

      Aranda May, Montserrat (Universitat Politècnica de Catalunya, 2013-06)
      Bachelor thesis
      Open Access
      L'objectiu d'aquest treball és estudiar les propietats del conjunt de nombres reals, començant per una construcció d'aquest conjunt a través de classes d'equivalència de successions de Cauchy. Posteriorment, es prendrà ...
    • Constraint algorithm for k-presymplectic hamiltonian systems: application to singular field theories 

      Gràcia Sabaté, Francesc Xavier; Martín Grillo, Rubén; Román Roy, Narciso (World Scientific and Engineering Academy and Society (WSEAS), 2009-08-01)
      Article
      Open Access
      The k-symplectic formulation of field theories is specially simple, since only tangent and cotangent bundles are needed in its description. Its defining elements show a close relationship with those in the symplectic formulation ...
    • Constraint algorithm for singular field theories in the k-cosymplectic framework 

      Gràcia Sabaté, Francesc Xavier; Rivas Guijarro, Xavier; Román Roy, Narciso (American Institute of Mathematical Sciences, 2020-03-15)
      Article
      Restricted access - publisher's policy
      The aim of this paper is to develop a constraint algorithm for singular classical field theories in the framework of k-cosymplectic geometry. Since these field theories are singular, we need to introduce the notion of ...
    • Ferroelectrics as smart mechanical materials 

      Cordero Edwards, Kumara; Domingo Marimon, Neus; Abdollahi Hosnijeh, Amir; Sort Viñas, Jordi; Catalan, Gustau (2017-07-21)
      Article
      Open Access
      The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the ...
    • Galois: entre els radicals 

      Lario Loyo, Joan Carles (2012-10-03)
      Audiovisual
      Open Access
    • Generic Galois extensions for SL_2(F_5) over Q 

      Plans Berenguer, Bernat (Mathematical Publishing, 2007)
      Article
      Open Access
      Let $G_n$ be a double cover of either the alternating group $A_n$ or the symmetric group $S_n$, and let $G_{n-1}$ be the corresponding double cover of $A_{n-1}$ or $S_{n-1}$. For every odd $n\geq 3$ and every field $k$ of ...
    • Grupos de Galois lineales provenientes de la geometría 

      Dieulefait, Luís V. (2013-03-06)
      Audiovisual
      Open Access
    • Hamilton-Jacobi theory in multisymplectic classical field theories 

      De León, Manuel; Prieto Martínez, Pedro Daniel; Román Roy, Narciso; Vilariño Fernández, Silvia (2017-09-01)
      Article
      Open Access
      The geometric framework for the Hamilton-Jacobi theory developed in the studies of Carinena et al. [Int. J. Geom. Methods Mod. Phys. 3(7), 1417-1458 (2006)], Carinena et al. [Int. J. Geom. Methods Mod. Phys. 13(2), 1650017 ...
    • Higher-order Cartan symmetries in k-symplectic field theory 

      Román Roy, Narciso; Salgado, Modesto; Vilariño, Silvia (2008-04-30)
      Article
      Open Access
      For k-symplectic Hamiltonian field theories, we study infinitesimal transformations generated by certain kinds of vector fields which are not Noether symmetries, but which allow us to obtain conservation laws by means ...
    • Hopf Galois structures on symmetric and alternating extensions 

      Río Doval, Ana; Vela del Olmo, Maria Montserrat; Crespo Vicente, Teresa (2018)
      Article
      Open Access
      By using a recent theorem by Koch, Kohl, Truman and Underwood on normality, we determine that some types of Hopf Galois structures do not occur on Galois extensions with Galois group isomorphic to alternating or symmetric ...
    • Induced Hopf Galois structures 

      Crespo Vicente, Teresa; Río Doval, Ana; Vela del Olmo, Maria Montserrat (2016-07-01)
      Article
      Open Access
      For a ¿nite Galois extension K/k and an intermediate ¿eld F such that Gal(K/F)has a normal complement in Gal(K/k), we construct and characterize Hopf Galois structures on K/k which are induced by a pair of Hopf Galois ...
    • Lectura de la memòria sobre la resolubilitat de les equacions per radicals 

      Pla i Carrera, Josep (2013-03-06)
      Audiovisual
      Open Access
    • Multisymplectic Lagrangian and Hamiltonian formalisms of classical field theories 

      Román Roy, Narciso (2009)
      Article
      Open Access
      This review paper is devoted to presenting the standard multisymplectic formulation for describing geometrically classical field theories, both the regular and singular cases. First, the main features of the Lagrangian ...
    • Multisymplectic unified formalism for Einstein-Hilbert gravity 

      Gaset Rifà, Jordi; Román Roy, Narciso (2018-03-01)
      Article
      Open Access
      We present a covariant multisymplectic formulation for the Einstein-Hilbert model of General Relativity. As it is described by a second-order singular Lagrangian, this is a gauge field theory with constraints. The use of ...
    • New multisymplectic approach to the Metric-Affine (Einstein-Palatini) action for gravity 

      Gaset Rifa, Jordi; Román Roy, Narciso (American Institute of Mathematical Sciences, 2019-09-01)
      Article
      Open Access
      We present a covariant multisymplectic formulation for the Einstein-Palatini (or Metric-Affine) model of General Relativity (without energy-matter sources). As it is described by a first-order affine Lagrangian (in the ...
    • Non-isomorphic Hopf Galois structures with isomorphic underlying Hopf algebras 

      Crespo, Teresa; Río Doval, Ana; Vela del Olmo, Maria Montserrat (2014-10-30)
      Article
      Restricted access - publisher's policy
      We give a degree 8 non-normal separable extension having two non-isomorphic Hopf Galois structures with isomorphic underlying Hopf algebras.
    • On the k-symplectic, k-cosymplectic and multisymplectic formalisms of classical field theories 

      Román Roy, Narciso; Rey, Angel M.; Salgado, Modesto; Vilariño, Silvia (2007-05-31)
      Article
      Open Access
      The objective of this work is twofold: First, we analyze the relation between the kcosymplectic and the k-symplectic Hamiltonian and Lagrangian formalisms in classical field theories. In particular, we prove the equivalence ...
    • El Problema invers de la teoria de Galois 

      Plans Berenguer, Bernat (2013-03-06)
      Audiovisual
      Open Access
    • Remarks on multisymplectic reduction 

      Echeverría Enríquez, Arturo; Muñoz Lecanda, Miguel Carlos; Román Roy, Narciso (2018-06-01)
      Article
      Open Access
      The problem of reduction of multisymplectic manifolds by the action of Lie groups is stated and discussed, as a previous step to give a fully covariant scheme of reduction for classical field theories with symmetries.
    • Revisiting Kneser’s theorem for field extensions 

      Bachoc, Christine; Serra Albó, Oriol; Zemor, Gilles (2017-05-31)
      Article
      Open Access
      A Theorem of Hou, Leung and Xiang generalised Kneser’s addition Theorem to field extensions. This theorem was known to be valid only in separable extensions, and it was a conjecture of Hou that it should be valid for all ...