Browsing Artículos (Álgebra) by Title
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Fast algorithmic NielsenThurston classification of fourstrand braids [Article]
(World Scientific Publishing, 201204)We give an algorithm which decides the NielsenThurston type of a given fourstrand braid. The complexity of our algorithm is quadratic with respect to word length. The proof of its validity is based on a result which ...

Fast NielsenThurston classification of braids [Article]
(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.

Finite monodromy of some families of exponential sums [Article]
(Elsevier, 201904)Given a prime p and an integer d > 1, we give a numerical criterion to decide whether the ℓadic sheaf associated to the oneparameter exponential sums t 7→P x ψ(xd + tx) over Fp has finite monodromy or not, and work ...

Fonctions zêta ℓmodulaires [Article]
(Duke University Press, 2012)Soient F un corps commutatif localement compact non archimédien, de caractéristique résiduelle notée p, et D une Falgèbre à division centrale de dimension finie. Soit un nombre premier différent de p. Dans cet ...

Formal groups, supersingular abelian varieties and tame ramification [Article]
(Elsevier, 20110515)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 ℓtorsion points of the variety ...

Free divisors and duality for Dmodules [Article]
(Pleiades, 2002)The relationship between Dmodules 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 Dmodules ...

Galois Theory, discriminants and torsion subgroups of elliptic curves [Article]
(Elsevier, 201008)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 ...

Generating random braids [Article]
(Elsevier, 201301)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 ...

Geometric approaches to braid groups and mapping class groups [Article]
(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 ...

Geometric embeddings of braid groups do not merge conjugacy classes [Article]
(Sociedad Matemática Mexicana, 201410)An embedding of the mtimes punctured disc into the ntimes 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 ...

Gevrey expansions of hypergeometric integrals I [Article]
(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 ...

Gevrey solutions of irregular hypergeometric systems in two variables [Article]
(Elsevier, 20110801)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 ...

Gevrey solutions of the irregular hypergeometric system associated with an affine monomial curve [Article]
(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 ...

Godement resolutions and sheaf homotopy theory [Article]
(Springer, 201509)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 ...

Grothendieck bialgebras, Partition lattices, and symmetric functions in noncommutative variables [Article]
(American Mathematical Society, 2006)We show that the Grothendieck bialgebra of the semitower of partition lattice algebras is isomorphic to the graded dual of the bialgebra of symmetric functions in noncommutative variables. In particular this isomorphism ...

Gröbner δbases and Gröbner bases for differential operators [Article]
(Polish Academy of Sciences, Institute of Mathematics, 2002)This paper deals with the notion of Gr¨obner δbase 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 ...

HasseSchmidt derivations and coefficient fields in positive characteristics [Article]
(Elsevier, 20030701)We show how to express any HasseSchmidt 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 ...

HasseSchmidt derivations, divided powers and differential smoothness [Article]
(Association des Annales de l'Institut Fourier, 2009)Let k be a commutative ring, A a commutative kalgebra and D the filtered ring of klinear differential operators of A. We prove that: (1) The graded ring gr D admits a canonical embedding θ into the graded dual of the ...

Hironaka's characteristic polygon and effective resolution of surfaces [Article]
(Elsevier, 20070301)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 ...

Homotopy theory of bicomplexes [Article]
(Elsevier, 201905)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 ...