Now showing items 68-87 of 209

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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 ...
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      Galois Theory, discriminants and torsion subgroups of elliptic curves  [Article]

      García Selfa, Irene; González Jiménez, Enrique; Tornero Sánchez, José María (Elsevier, 2010-08)
      We find a tight relationship between the torsion subgroup and the image of the mod 2 Galois representation associated to an elliptic curve defined over the rationals. This is shown using some characterizations for the ...
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      Generating random braids  [Article]

      Gebhardt, Volker; González-Meneses López, Juan (Elsevier, 2013-01)
      We present an algorithm to generate positive braids of a given length as words in Artin generators with a uniform probability. The complexity of this algorithm is polynomial in the number of strands and in the length of ...
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      Geometric approaches to braid groups and mapping class groups  [Article]

      González-Meneses López, Juan (Cellule Mathdoc, 2015)
      These are Lecture Notes of a course given by the author at the School Winter Braids, held at the Université de Pau et des Pays de L’Adour (France), on February 2015. It is explained how mapping class groups, and in particular ...
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      Geometric embeddings of braid groups do not merge conjugacy classes  [Article]

      González-Meneses López, Juan (Sociedad Matemática Mexicana, 2014-10)
      An embedding of the m-times punctured disc into the n-times punctured disc, for n > m, yields an embedding of the braid group on m strands Bm into the braid group on n strands Bn, called a geometric embedding. The main ...
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      Gevrey expansions of hypergeometric integrals I  [Article]

      Castro Jiménez, Francisco Jesús; Granger, Michel (Oxford University Press, 2015)
      We study integral representations of the Gevrey series solutions of irregular hypergeometric systems. In this paper we consider the case of the systems associated with a one row matrix, for which the integration domains ...
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      Gevrey solutions of irregular hypergeometric systems in two variables  [Article]

      Fernández Fernández, María Cruz; Castro Jiménez, Francisco Jesús (Elsevier, 2011-08-01)
      We describe the Gevrey series solutions at singular points of the irregular hypergeometric system (GKZ system) associated with an affine plane monomial curve. We also describe the irregularity complex of such a system with ...
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      Gevrey solutions of the irregular hypergeometric system associated with an affine monomial curve  [Article]

      Fernández Fernández, María Cruz; Castro Jiménez, Francisco Jesús (American Mathematical Society, 2011)
      We describe the Gevrey series solutions at singular points of the irregular hypergeometric system (GKZ system) associated with an affine monomial curve. We also describe the irregularity complex of such a system with respect ...
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      Godement resolutions and sheaf homotopy theory  [Article]

      Rodríguez González, Beatriz; Roig Marti, Agusti (Springer, 2015-09)
      The Godement cosimplicial resolution is available for a wide range of categories of sheaves. In this paper we investigate under which conditions of the Grothendieck site and the category of coefficients it can be used to ...
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      Grothendieck bialgebras, Partition lattices, and symmetric functions in noncommutative variables  [Article]

      Bergeron, Nantel; Hohlweg, Christophe; Rosas Celis, Mercedes Helena; Zabrocki, Mike (American Mathematical Society, 2006)
      We show that the Grothendieck bialgebra of the semi-tower of partition lattice algebras is isomorphic to the graded dual of the bialgebra of symmetric functions in noncommutative variables. In particular this isomorphism ...
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      Gröbner δ-bases and Gröbner bases for differential operators  [Article]

      Castro Jiménez, Francisco Jesús; Moreno Frías, María Ángeles (Polish Academy of Sciences, Institute of Mathematics, 2002)
      This paper deals with the notion of Gr¨obner δ-base for some rings of linear differential operators by adapting the works of W. Trinks, A. Assi, M. Insa and F. Pauer. We compare this notion with the one of Gröbner base for ...
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      Hasse-Schmidt derivations and coefficient fields in positive characteristics  [Article]

      Fernández Lebrón, María Magdalena; Narváez Macarro, Luis (Elsevier, 2003-07-01)
      We show how to express any Hasse-Schmidt derivation of an algebra in terms of a finite number of them under natural hypothesis. As an application, we obtain coefficient fields of the completion of a regular local ring of ...
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      Hasse-Schmidt derivations, divided powers and differential smoothness  [Article]

      Narváez Macarro, Luis (Association des Annales de l'Institut Fourier, 2009)
      Let k be a commutative ring, A a commutative k-algebra and D the filtered ring of k-linear differential operators of A. We prove that: (1) The graded ring gr D admits a canonical embedding θ into the graded dual of the ...
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      Hironaka's characteristic polygon and effective resolution of surfaces  [Article]

      Piedra Sánchez, Ramón; Tornero Sánchez, José María (Elsevier, 2007-03-01)
      Hironaka’s concept of characteristic polyhedron of a singularity has been one of the most powerful and fruitful ideas of the last decades in singularity theory. In fact, since then combinatorics have become a major tool ...
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      Homotopy theory of bicomplexes  [Article]

      Muro Jiménez, Fernando; Roitzheim, Constanze (Elsevier, 2019-05)
      We define two model structures on the category of bicomplexes concentrated in the right half plane. The first model structure has weak equivalences detected by the totalisation functor. The second model structure’s weak ...