Now showing items 55-74 of 211

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      Echelons of power series and Gabrielov’s counterexample to nested linear Artin Approximation  [Article]

      Alonso García, María Emilia; Castro Jiménez, Francisco Jesús; Hauser, Herwig; Koutschan, Christoph (London Mathematical Society, 2018)
      Gabrielov’s famous example for the failure of analytic Artin approximation in the presence of nested subring conditions is shown to be due to a growth phenomenon in standard basis computations for echelons, a generalization ...
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      En recuerdo de Alexander Grothendieck: prólogo para una lectura de su vida y obra  [Article]

      Narváez Macarro, Luis (Real Sociedad Matemática Española, 2017)
      En este artículo repasamos algunas de las claves de las contribuciones matemáticas de Alexander Grothendieck y del contexto en el que se gestaron, y nos asomamos así a la vida y obra de una de las figuras más influyentes ...
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      Encoding algebraic power series  [Article]

      Alonso García, María Emilia; Castro Jiménez, Francisco Jesús; Hauser, Herwig (Springer, 2017)
      The division algorithm for ideals of algebraic power series satisfying Hironaka’s box condition is shown to be finite when expressed suitably in terms of the defining polynomial codes of the series. In particular, the codes ...
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      Entrevista a Isabel Fernández, conferenciante invitada al ICM 2010  [Article]

      Muro Jiménez, Fernando (Real Sociedad Matematica Española, 2010)
      Isabel Fernández, de la Universidad de Sevilla, es conferenciante invitada junto con Pablo Mira (Universidad Politécnica de Cartagena) a la sección de Geometría del próximo ICM, que se celebrará en agosto en Hyderabad ...
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      Equimultiple locus of embedded algebroid surfaces and blowing-up in arbitrary characteristic  [Article]

      Piedra Sánchez, Ramón; Tornero Sánchez, José María (Chinese Academy of Sciences, 2009-12)
      This paper extends previous results of the authors, concerning the behaviour of the equimultiple locus of algebroid surfaces under blowing–up, to arbitrary characteristic.
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      Equimultiple locus of embedded algebroid surfaces and blowing-up in characteristic zero  [Article]

      Piedra Sánchez, Ramón; Tornero Sánchez, José María (Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, 2004)
      The smooth equimultiple locus of embedded algebroid surfaces appears naturally in many resolution process, both classical and modern.In this paper we explore how it changes by blowing–up.
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      Estimates for exponential sums with a large automorphism group  [Article]

      Rojas León, Antonio (American Mathematical Society, 2012)
      We prove some improvements of the classical Weil bound for one variable additive and multiplicative character sums associated to a polynomial over a finite field k = Fq for two classes of polynomials which are invariant ...
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      Estimates for singular multiplicative character sums  [Article]

      Rojas León, Antonio (Duke University Press, 2005)
      We give some estimates for multiplicative character sums on quasiprojective varieties over finite fields depending on the severity of the singularities of the variety at infinity. We also remove the hypothesis of ...
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      Exact cost minimization of a series-parallel reliable system with multiple component choices using an algebraic method  [Article]

      Gago Vargas, Manuel Jesús; Hartillo Hermoso, Isabel; Puerto Albandoz, Justo; Ucha Enríquez, José María (2013-11)
      The redundancy allocation problem is formulated minimizing the design cost for a series-parallel system with multiple component choices while ensuring a given system reliability level. The obtained model is a nonlinear ...
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      Explicit calculations in rings of differential operators  [Article]

      Castro Jiménez, Francisco Jesús; Granger, Michel (Société Mathématique de France, 2004)
      We use the notion of a standard basis to study algebras of linear differential operators and finite type modules over these algebras. We consider the polynomial and the holomorphic cases as well as the formal case. Our ...
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      Explicit local multiplicative convolution of ℓ-adic sheaves  [Article]

      Rojas León, Antonio (European Mathematical Society, 2018)
      We give explicit formulas for the local multiplicative convolution functors, which express the local monodromies of the convolution of two ℓ-adic sheaves on the torus Gm over the algebraic closure of a finite field in terms ...
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      Explicit models for perverse sheaves  [Article]

      Gudiel Rodríguez, Félix; Narváez Macarro, Luis (European Mathematical Society, 2003)
      We consider categories of generalized perverse sheaves, with relaxed constructibility conditions, by means of the process of gluing t-structures and we exhibit explicit abelian categories defined in terms of standard sheaves ...
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      Exponential growth of rank jumps for A-hypergeometric systems  [Article]

      Fernández Fernández, María Cruz (European Mathematical Society, 2013)
      The dimension of the space of holomorphic solutions at nonsingular points (also called the holonomic rank) of a A–hypergeometric system MA(β) is known to be bounded above by 22d vol(A) [SST00], where d is the rank of ...
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      Extending a valuation centered in a local domain to the formal completion  [Article]

      Herrera Govantes, Francisco Javier; Olalla Acosta, Miguel Ángel; Spivakovsky, Mark; Teissier, Bernard (London Mathematical Society, 2012-09)
      Let (R; m; k) be a local noetherian domain with field of fractions K and R_v a valuation ring, dominating R (not necessarily birationally). Let v|K be the restriction of v to K; by definition, v|K is centered at R. Let ...
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      Fast algorithmic Nielsen-Thurston classification of four-strand braids  [Article]

      Calvez, Matthieu; Wiest, Bert (World Scientific Publishing, 2012-04)
      We give an algorithm which decides the Nielsen-Thurston type of a given four-strand braid. The complexity of our algorithm is quadratic with respect to word length. The proof of its validity is based on a result which ...
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      Fast Nielsen-Thurston classification of braids  [Article]

      Calvez, Matthieu (Mathematical Sciences Publishers, 2014)
      We prove the existence of an algorithm that solves the reducibility problem in braid groups and runs in quadratic time with respect to the braid length for any fixed braid index.
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      Finite monodromy of some families of exponential sums  [Article]

      Rojas León, Antonio (Elsevier, 2019-04)
      Given a prime p and an integer d > 1, we give a numerical criterion to decide whether the ℓ-adic sheaf associated to the one-parameter exponential sums t 7→P x ψ(xd + tx) over Fp has finite monodromy or not, and work ...
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      Fonctions zêta ℓ-modulaires  [Article]

      Mínguez Espallargas, Alberto (Duke University Press, 2012)
      Soient F un corps commutatif localement compact non archimédien, de caractéristique résiduelle notée p, et D une F-algèbre à division centrale de dimension finie. Soit un nombre premier différent de p. Dans cet ...
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      Formal groups, supersingular abelian varieties and tame ramification  [Article]

      Arias de Reyna Domínguez, Sara (Elsevier, 2011-05-15)
      Let us consider an abelian variety defined over Qℓ with good supersingular reduction. In this paper we give explicit conditions that ensure that the action of the wild inertia group on the ℓ-torsion points of the variety ...
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      Free divisors and duality for D-modules  [Article]

      Castro Jiménez, Francisco Jesús; Ucha Enríquez, José María (Pleiades, 2002)
      The relationship between D-modules and free divisors has been studied in a general setting by L. Narváez and F.J. Calderón. Using the ideas of these works we prove in this article a duality formula between two D-modules ...