Now showing items 74-93 of 209

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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 ...
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      Homotopy theory of non-symmetric operads, II: Change of base category and left properness  [Article]

      Muro Jiménez, Fernando (Mathematical Sciences Publishers, 2014)
      We prove, under mild assumptions, that a Quillen equivalence between symmetric monoidal model categories gives rise to a Quillen equivalence between their model categories of (non-symmetric) operads, and also between model ...
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      Homotopy theory of nonsymmetric operads  [Article]

      Muro Jiménez, Fernando (Mathematical Sciences Publishers, 2011)
      We endow categories of nonsymmetric operads with natural model structures. We work with no restriction on our operads and only assume the usual hypotheses for model categories with a symmetric monoidal structure. We also ...
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      Homotopy units in A-infinity algebras  [Article]

      Muro Jiménez, Fernando (American Mathematical Society, 2016-03)
      We show that the canonical map from the associative operad to the unital associative operad is a homotopy epimorphism for a wide class of symmetric monoidal model categories. As a consequence, the space of unital associative ...
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      How to calculate the slopes of a D-module  [Article]

      Assi, Abdallah; Castro Jiménez, Francisco Jesús; Granger, Michel (Foundation Compositio Mathematica, 1996)
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      Improvements of the Weil bound for Artin-Schreier curves  [Article]

      Rojas León, Antonio; Wan, Daqing (Springer, 2011-10)
      For the Artin-Schreier curve y q − y = f(x) defined over a finite field Fq of q elements, the celebrated Weil bound for the number of Fq r -rational points can be sharp, especially in super-singular cases and when r is ...
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      Improving an algorithm to solve multiple simultaneous conjugacy problems in braid groups  [Article]

      González-Meneses López, Juan (American Mathematical Society, 2005)
      There are recent cryptographic protocols that are based on Multiple Simultaneous Conjugacy Problems in braid groups. We improve an algorithm, due to Sang Jin Lee and Eonkyung Lee, to solve these problems, by applying a ...