Now showing items 26-45 of 209

    • IconClassification of subgroups of symplectic groups over finite fields containing a transvection  [Article]

      Arias de Reyna Domínguez, Sara; Dieulefait, Luis Víctor; Wiese, Gabor (De Gruyter Open, 2016-06)
      In this note, we give a self-contained proof of the following classification (up to conjugation) of finite subgroups of GSpnpF`q containing a nontrivial transvection for ≥ 5, which can be derived from work of Kantor: G ...
    • IconClosures of positive braids and the Morton-Franks-Williams inequality  [Article]

      González-Meneses López, Juan; González Manchón, Pedro María (Elsevier, 2014-09-01)
      We study the Morton-Franks-Williams inequality for closures of simple braids (also known as positive permutation braids). This allows to prove, in a simple way, that the set of simple braids is a orthonormal basis for the ...
    • IconCoefficient fields and scalar extension in positive characteristic  [Article]

      Fernández Lebrón, María Magdalena; Narváez Macarro, Luis (Elsevier, 2005-03-15)
      Let k be a perfect field of positive characteristic, k(t)per the perfect closure of k(t) and A = k[[X1, . . . , Xn]]. We show that for any maximal ideal n of A′ = k(t)per ⊗k A, the elements in Ac′ n which are annihilated ...
    • IconCohomologie évanescente p-adique: calculs locaux  [Article]

      Gros, Michel; Narváez Macarro, Luis (Università di Padova, 2000)
    • IconCombinatorics of syzygies for semigroup algebras  [Article]

      Briales Morales, Emilio; Pisón Casares, Pilar (Universitat de Barcelona, 1998)
      We describe how the graded minimal resolution of certain semigroup algebras is related to the combinatorics of some simplicial complexes. We obtain characterizations of the Cohen-Macaulay and Gorenstein conditions. The ...
    • IconCombinatorics on a family of reduced Kronecker coefficients  [Article]

      Colmenarejo Hernando, Laura; Rosas Celis, Mercedes Helena (Elsevier, 2015-10)
      The reduced Kronecker coefficients are particular instances of Kronecker coefficients that contain enough information to recover them. In this notes we compute the generating function of a family of reduced Kronecker ...
    • IconCommutation and normal ordering for operators on symmetric functions  [Article]

      Briand, Emmanuel; McNamara, Peter R. W.; Orellana, Rosa C.; Rosas Celis, Mercedes Helena (2015)
      We study the commutation relations and normal ordering between families of operators on symmetric functions. These operators can be naturally defined by the operations of multiplication, Kronecker product, and their ...
    • IconComparison of theoretical complexities of two methods for computing annihilating ideals of polynomials  [Article]

      Gago Vargas, Manuel Jesús; Hartillo Hermoso, Isabel; Ucha Enríquez, José María (2005)
      Let f1, . . . , fp be polynomials in C[x1, . . . , xn] and let D = Dn be the n-th Weyl algebra. We provide upper bounds for the complexity of computing the annihilating ideal of f s = f s1 1 · · · f sp p in D[s] = D[s1, . ...
    • IconCompatible systems of symplectic Galois representations and the inverse Galois problem I. Images of projective representations  [Article]

      Arias de Reyna Domínguez, Sara; Dieulefait, Luis Víctor; Wiese, Gabor (American Mathematical Society, 2017-02)
      This article is the first part of a series of three articles about compatible systems of symplectic Galois representations and applications to the inverse Galois problem. In this first part, we determine the smallest field ...
    • IconCompatible systems of symplectic Galois representations and the inverse Galois problem II. Transvections and huge image  [Article]

      Arias de Reyna Domínguez, Sara; Dieulefait, Luis Víctor; Wiese, Gabor (Mathematical Sciences Publishers, 2016-03)
      This article is the second part of a series of three articles about compatible systems of symplectic Galois representations and applications to the inverse Galois problem. This part is concerned with symplectic Galois ...
    • IconCompatible systems of symplectic Galois representations and the inverse Galois problem III. Automorphic construction of compatible systems with suitable local properties  [Article]

      Arias de Reyna Domínguez, Sara; Dieulefait, Luis Víctor; Shin, Sug Woo; Wiese, Gabor (Springer, 2015-04)
      This article is the third and last part of a series of three articles about compatible systems of symplectic Galois representations and applications to the inverse Galois problem. This part proves the following new result ...
    • IconComputation of centralizers in braid groups and Garside groups  [Article]

      Gonçalves Soares Franco, Nuno María; González-Meneses López, Juan (Consejo Superior de Investigaciones Científicas, 2003)
      We give a new method to compute the centralizer of an element in Artin braid groups and, more generally, in Garside groups. This method, together with the solution of the conjugacy problem given by the authors in [9] ...
    • IconComputational methods in algebra and analysis  [Article]

      Castro Jiménez, Francisco Jesús (Sociedad Española de Matemática Aplicada, 2007-09)
      This paper describes some applications of Computer Algebra to Algebraic Analysis also known as D-module theory, i.e. the algebraic study of the systems of linear partial differential equations. Gröbner bases for rings ...
    • IconComputing the rational torsion of an elliptic curve using Tate normal form  [Article]

      García Selfa, Irene; Olalla Acosta, Miguel Ángel; Tornero Sánchez, José María (Elsevier, 2002-09)
      It is a classical result (apparently due to Tate) that all elliptic curves with a torsion point of order n (4 ≤ n ≤ 10, or n = 12) lie in a oneparameter family. However, this fact does not appear to have been used ever for ...
    • IconConjugacy in Garside groups I: Cyclings, powers, and rigidity  [Article]

      Birman, Joan S.; Gebhardt, Volker; González-Meneses López, Juan (European Mathematical Society, 2007)
      In this paper a relation between iterated cyclings and iterated powers of elements in a Garside group is shown. This yields a characterization of elements in a Garside group having a rigid power, where ‘rigid’ means that ...
    • IconConjugacy in Garside groups II: Structure of the ultra summit set  [Article]

      Birman, Joan S.; Gebhardt, Volker; González-Meneses López, Juan (European Mathematical Society, 2008)
      This paper is the second in a series in which the authors study the conjugacy decision problem (CDP) and the conjugacy search problem (CSP) in Garside groups. The ultra summit set USS(X) of an element X in a Garside group ...
    • IconConjugacy in Garside Groups III: Periodic braids  [Article]

      Birman, Joan S.; Gebhardt, Volker; González-Meneses López, Juan (Elsevier, 2007-10-15)
      An element in Artin’s braid group Bn is said to be periodic if some power of it lies in the center of Bn. In this paper we prove that all previously known algorithms for solving the conjugacy search problem in Bn are ...
    • IconConjugacy problem for braid groups and Garside groups  [Article]

      Gonçalves Soares Franco, Nuno María; González-Meneses López, Juan (Elsevier, 2003-08-01)
      We present a new algorithm to solve the conjugacy problem in Artin braid groups, which is faster than the one presented by Birman, Ko and Lee. This algorithm can be applied not only to braid groups, but to all Garside ...
    • IconConservation of the noetherianity by perfect transcendental field extensions  [Article]

      Fernández Lebrón, María Magdalena; Narváez Macarro, Luis (European Mathematical Society, 2003)
      Let k be a perfect field of characteristic p>0, k(t)per the perfect closure of k(t) and A a k-algebra. We characterize whether the ring A⊗kk(t)per is noetherian when A is the ring of formal power series in n indeterminates over k.
    • IconConstructions in R[x_1, ..., x_n]. Applications to K-Theory  [Article]

      Gago Vargas, Manuel Jesús (2002-06-25)
      A classical result in K-Theory about polynomial rings like the Quillen-Suslin theorem admits an algorithmic approach when the ring of coefficients has some computational properties, associated with Gröbner bases. There ...