Search

Your search keyword '"Departamento de Álgebra [Madrid]"' showing total 12 results
Start Over Author "Departamento de Álgebra [Madrid]" Topic 01 natural sciences
12 results on '"Departamento de Álgebra [Madrid]"'

1. On a theorem by de Felipe and Teissier about the comparison of two henselisations in the non-noetherian case

Author

María Emilia Alonso García, Stefan Neuwirth, Henri Lombardi, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Laboratoire de Mathématiques de Besançon (UMR 6623) (LMB), Université de Bourgogne (UB)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), María Emilia Alonso García was partially supported by the Instituto de Matemática Interdisciplinar (IMI)., ANR-19-CE40-0002,ANCG,Analyse non commutative sur les groupes et les groupes quantiques(2019), Universidad Complutense de Madrid [Madrid] (UCM), Fédération Bourgogne Franche-Comté Mathématiques (BFC-Math ), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)

Subjects
Noetherian, Pure mathematics, [MATH.MATH-AC]Mathematics [math]/Commutative Algebra [math.AC], Field (mathematics), Commutative Algebra (math.AC), 01 natural sciences, Constructive, Mathematics - Algebraic Geometry, minimal valuation, 0103 physical sciences, FOS: Mathematics, MSC 2020: 13B40 13J15 12J10 14B25, 0101 mathematics, Algebraic number, Algebraic Geometry (math.AG), Quotient, Mathematics, Valuation (algebra), Algebra and Number Theory, 010102 general mathematics, Local ring, Mathematics - Commutative Algebra, henselisation of a residually discrete local ring, henselisation of a valuated discrete field, Maximal ideal, 010307 mathematical physics
Abstract

Let R be a local domain, v a valuation of its quotient field centred in R at its maximal ideal. We investigate the relationship between R h , the henselisation of R as local ring, and v ˜ , the henselisation of the valuation v, by focussing on the recent result by de Felipe and Teissier referred to in the title. We give a new proof that simplifies the original one by using purely algebraic arguments. This proof is moreover constructive in the sense of Bishop and previous work of the authors, and allows us to obtain as a by-product a (slight) generalisation of the theorem by de Felipe and Teissier.

Published
2021
Full Text
View/download PDF

2. Motivic Poincaré series, toric singularities and logarithmic Jacobian ideals

Author

Pedro Daniel González Pérez, Helena Cobo Pablos, Universidad de Sevilla. Departamento de álgebra, Universidad de Sevilla. FQM218: Geometria Algebraica, Sistemas Diferenciales y Singularidades, Ministerio de Educación y Ciencia (MEC). España, Fundación Caja Madrid, Departamento de Álgebra [Madrid], and Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM)

Subjects
Monomial, Pure mathematics, Differential form, toric geometry, 01 natural sciences, Mathematics - Algebraic Geometry, Mathematics::Algebraic Geometry, 0103 physical sciences, Geometric motivic Poincaré series, 0101 mathematics, Mathematics, Ring (mathematics), Sequence, Algebra and Number Theory, geometric motivic Poincaré series, Mathematics::Commutative Algebra, Series (mathematics), Computer Science::Information Retrieval, 010102 general mathematics, Toric geometry, Toric variety, 14B05, 14J17,14M25, 16. Peace & justice, Arc spaces, Algebra, Mathematics::Logic, Poincaré series, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], 010307 mathematical physics, Geometry and Topology, Variety (universal algebra), Singularities, singularities, arc spaces
Abstract

The geometric motivic Poincar\'e series of a variety, which was introduced by Denef and Loeser, takes into account the classes in the Grothendieck ring of the sequence of jets of arcs in the variety. Denef and Loeser proved that this series has a rational form. We describe it in the case of an affine toric variety of arbitrary dimension. The result, which provides an explicit set of candidate poles, is expressed in terms of the sequence of Newton polyhedra of certain monomial ideals, which we call logarithmic jacobian ideals, associated to the modules of differential forms with logarithmic poles outside the torus of the toric variety., Comment: to appear in Journal of Algebraic Geometry

Published
2011
Full Text
View/download PDF

3. Motivic Milnor fiber of a quasi-ordinary hypersurface

Author

Manuel González Villa, Pedro Daniel González Pérez, Departamento de Álgebra [Madrid], and Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM)

Subjects
Pure mathematics, quasi-ordinary singularities, General Mathematics, MSC(2000): 32S25, 32S45, 32S35, 14M25, 01 natural sciences, Spectrum (topology), Mathematics - Algebraic Geometry, Mathematics::Algebraic Geometry, Álgebra, 0103 physical sciences, FOS: Mathematics, topological zeta function, Topological invariants, Germ, Fiber, 0101 mathematics, Algebraic Geometry (math.AG), Mathematics, Mathematics::Complex Variables, Applied Mathematics, 010102 general mathematics, Mathematical analysis, Zero (complex analysis), Igusa zeta-function, motivic Igusa zeta function, Hypersurface, Geometria algebraica, Hodge-Steenbrink spectrum, 010307 mathematical physics, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], Analytic function
Abstract

Let f : ( 𝐂 d + 1 , 0 ) → ( 𝐂 , 0 ) $f \hspace{-1.0pt}:\hspace{-1.0pt}(\mathbf {C}^{d+1}, 0) \hspace{-1.0pt}\rightarrow \hspace{-1.0pt}(\mathbf {C},0)$ be a germ of complex analytic function such that its zero level defines an irreducible germ of quasi-ordinary hypersurface ( S , 0 ) ⊂ ( 𝐂 d + 1 , 0 ) $(S, 0) \subset (\mathbf {C}^{d+1}, 0)$ . We describe the motivic Igusa zeta function, the motivic Milnor fibre and the Hodge–Steenbrink spectrum of f at 0 in terms of topological invariants of ( S , 0 ) ⊂ ( 𝐂 d + 1 , 0 ) $(S, 0) \subset (\mathbf {C}^{d+1}, 0)$ .

Published
2014

4. Arithmetic motivic Poincaré series of Toric varieties

Author

Helena Cobo Pablos, Pedro Daniel González Pérez, Universidad de Sevilla. Departamento de álgebra, Universidad de Sevilla. FQM218: Geometría Algebraica, Sistemas Diferenciales y Singularidades, Ministerio de Ciencia e Innovación (MICIN). España, Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Departamento de Álgebra [Madrid], and Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM)

Subjects
toric geometry, 01 natural sciences, Mathematics - Algebraic Geometry, Polyhedron, 0103 physical sciences, arithmetic motivic Poincaré series, 0101 mathematics, Invariant (mathematics), Arithmetic, 14M25, Finite set, Mathematics, 14B05, Algebra and Number Theory, Semigroup, 010102 general mathematics, Toric geometry, Toric variety, 14B05, 14J17,14M25, Arc spaces, Geometria algebraica, Arithmetic motivic Poincaré series, Poincaré series, Gravitational singularity, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], 010307 mathematical physics, Affine transformation, Singularities, singularities, arc spaces, 14J17
Abstract

The arithmetic motivic Poincaré series of a variety V defined over a field of characteristic zero is an invariant of singularities that was introduced by Denef and Loeser by analogy with the Serre–Oesterlé series in arithmetic geometry. They proved that this motivic series has a rational form that specializes to the Serre-Oesterlé series when V is defined over the integers. This invariant, which is known explicitly for a few classes of singularities, remains quite mysterious. In this paper, we study this motivic series when V is an affine toric variety. We obtain a formula for the rational form of this series in terms of the Newton polyhedra of the ideals of sums of combinations associated to the minimal system of generators of the semigroup of the toric variety. In particular, we explicitly deduce a finite set of candidate poles for this invariant. Ministerio de Ciencia e Innovación

Published
2013

5. A Root Isolation Algorithm for Sparse Univariate Polynomials

Author

María Emilia Alonso García, André Galligo, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Geometry, algebra, algorithms (GALAAD), Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), The first author was partially supported by Spanish organizations: IMI(UCM), UCM (Grupo 910444) and MEC (MTM2011-22435)., J. van der Hoeven and M. van Hoeij, eds., MathAmSud (11MATH-04-Complexity-Deterministic and probabilistic complexity of algorithms for solving equations), European Project: 214584,EC:FP7:PEOPLE,FP7-PEOPLE-2007-1-1-ITN,SAGA(2008), and Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université Nice Sophia Antipolis (... - 2019) (UNS)

Subjects
Monomial, Polynomial, Discretization, 010103 numerical & computational mathematics, 01 natural sciences, Combinatorics, Minimal polynomial (field theory), Generalized Budan-Fourier theorem, real univariate polynomial, Newton process, separation bounds, real root isolation, discretization, 0101 mathematics, Sturm's theorem, Mathematics, Discrete mathematics, [INFO.INFO-SC]Computer Science [cs]/Symbolic Computation [cs.SC], Zero of a function, 010102 general mathematics, Univariate, $\f$ Budan table, fewnomial, $\f$ virtual roots, Algorithm, Reciprocal, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract

8 double pages.; International audience; We consider a univariate polynomial f with real coefficients having a high degree $N$ but a rather small number $d+1$ of monomials, with $d\ll N$. Such a sparse polynomial has a number of real root smaller or equal to $d$. Our target is to find for each real root of $f$ an interval isolating this root from the others. The usual subdivision methods, relying either on Sturm sequences or Moebius transform followed by Descartes's rule of sign, destruct the sparse structure. Our approach relies on the generalized Budan-Fourier theorem of Coste, Lajous, Lombardi, Roy and the techniques developed in some previous works of Galligo. To such a $f$ is associated a set of $d + 1$ $\mathbb{F}$-derivatives. The Budan-Fourier function $V_f(x)$ counts the sign changes in the sequence of $\mathbb{F}$-derivatives of the $f$ evaluated at $x$. The values at which this function jumps are called the $\mathbb{F}$-virtual roots of $f$, these include the real roots of $f$. We also consider the augmented $\mathbb{F}$-virtual roots of $f$ and introduce a genericity property which eases our study. We present a real root isolation method and an algorithm which has been implemented in Maple. We rely on an improved generalized Budan-Fourier count applied to both the input polynomial and its reciprocal, together with Newton like approximation steps.

Published
2012

6. Quasi-ordinary singularities and Newton trees

Author

Pierrette Cassou-Noguès, Alejandro Melle Hernández, Ignacio Luengo Velasco, Enrique Artal Bartolo, Department of mathematics, University of Zaragoza - Universidad de Zaragoza [Zaragoza], Department of Algebra, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM)-Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut de Mathématiques de Bordeaux (IMB), and Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)

Subjects
14B05, 32S05, 32S10, Pure mathematics, Polynomial, General Mathematics, Astrophysics::High Energy Astrophysical Phenomena, 010102 general mathematics, MathematicsofComputing_NUMERICALANALYSIS, Newton polygon, 01 natural sciences, 010101 applied mathematics, Tree (descriptive set theory), Mathematics - Algebraic Geometry, Hypersurface, Singularity, Discriminant, Álgebra, Transversal (combinatorics), ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION, FOS: Mathematics, Gravitational singularity, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], 0101 mathematics, Algebraic Geometry (math.AG), Mathematics
Abstract

In this paper we study some properties of the class of nu-quasi-ordinary hypersurface singularities. They are defined by a very mild condition on its (projected) Newton polygon. We associate with them a Newton tree and characterize quasi-ordinary hypersurface singularities among nu-quasi-ordinary hypersurface singularities in terms of their Newton tree. A formula to compute the discriminant of a quasi-ordinary Weierstrass polynomial in terms of the decorations of its Newton tree is given. This allows to compute the discriminant avoiding the use of determinants and even for non Weierstrass prepared polynomials. This is important for applications like algorithmic resolutions. We compare the Newton tree of a quasi-ordinary singularity and those of its curve transversal sections. We show that the Newton trees of the transversal sections do not give the tree of the quasi-ordinary singularity in general. It does if we know that the Newton tree of the quasi-ordinary singularity has only one arrow., 32 pages

Published
2012

7. On the variety parameterizing completely decomposable polynomials

Author

Alessandra Bernardi, Enrique Arrondo, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Geometry, algebra, algorithms (GALAAD), Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), European Project: 252367,EC:FP7:PEOPLE,FP7-PEOPLE-2009-IEF,DECONSTRUCT(2010), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), Enrique Arrondo, and Alessandra Bernardi

Subjects
MAT/03 Geometria, Dimension (graph theory), 010103 numerical & computational mathematics, Commutative Algebra (math.AC), 01 natural sciences, Combinatorics, Mathematics - Algebraic Geometry, Mathematics::Algebraic Geometry, Grassmannian, FOS: Mathematics, 0101 mathematics, Algebraically closed field, Plucker, Algebraic Geometry (math.AG), Mathematics, Algebra and Number Theory, Degree (graph theory), Mathematics::Commutative Algebra, 010102 general mathematics, 14N05, 13P05, Decomposable polynomials, Secant varieties, Grassmannians, Veronese varieties, Mathematics - Commutative Algebra, Linear subspace, GRASSMANN VARIETY, Algebra, HIGHER SECANT VARIETIES, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], Variety (universal algebra), Osculating circle
Abstract

The purpose of this paper is to relate the variety parameterizing completely decomposable homogeneous polynomials of degree $d$ in $n+1$ variables on an algebraically closed field, called $\Split_{d}(\PP n)$, with the Grassmannian of $n-1$ dimensional projective subspaces of $\PP {n+d-1}$. We compute the dimension of some secant varieties to $\Split_{d}(\PP n)$ and find a counterexample to a conjecture that wanted its dimension related to the one of the secant variety to $\GG (n-1, n+d-1)$. Moreover by using an invariant embedding of the Veronse variety into the Pl\"ucker space, then we are able to compute the intersection of $\GG (n-1, n+d-1)$ with $\Split_{d}(\PP n)$, some of its secant variety, the tangential variety and the second osculating space to the Veronese variety., Comment: 30 pages

Published
2011
Full Text
View/download PDF

8. Approximate roots, toric resolutions and deformations of a plane branch

Author

Pedro Daniel González Pérez, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), and Supported by Programa Ramon y Cajal and by MTM2007-6798-C02-02 grants of Ministerio de Educación y Ciencia, Spain.

Subjects
Power series, Polynomial, Quartic plane curve, Monomial, Plane curve, General Mathematics, 2000 MSC Primary 14J17, Secondary 32S10, 14M25, deformations of a plane curve, 01 natural sciences, Mathematics - Algebraic Geometry, Mathematics::Algebraic Geometry, Álgebra, 0103 physical sciences, FOS: Mathematics, 0101 mathematics, 14M25, Algebraic Geometry (math.AG), Principal branch, 32S10, Mathematics, Mathematics::Commutative Algebra, Plane (geometry), 010102 general mathematics, Mathematical analysis, equisingularity criterion, approximate roots, Irreducibility, 010307 mathematical physics, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], 14J17
Abstract

We analyze the expansions in terms of the approximate roots of a Weierstrass polynomial $f$ defining a plane branch $(C,0)$, in the light of the toric embedded resolution of the branch. This leads to the definition of a class of (non equisingular) deformations of a plane branch $(C,0)$ supported on certain monomials in the approximate roots of $f$. As a consequence we find out a Kouchnirenko type formula for the Milnor number $(C,0)$. Our results provide a geometrical approach to Abhyankar's straight line conditions and its consequences. As an application we give an equisingularity criterion for a family of plane curves to be equisingular to a plane branch and we express it algorithmically., Comment: Includes a correction of the previous version of the paper

Published
2010

9. Interannual and decadal SST-forced responses of the West African monsoon

Author

Paolo Ruti, Sébastien Gervois, Juergen Bader, Belén Rodríguez-Fonseca, Pascal Roucou, Mathieu Joly, Teresa Losada, Elsa Mohino, Bernard Fontaine, Irene Polo, Fabrice Chauvin, Aurore Voldoire, Serge Janicot, Cyril Caminade, Javier García-Serrano, Université Madrid, Université de Madrid, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre de Recherches de Climatologie (CRC), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), UCM, Ente per le Nuove tecnologie, l'Energia e l'Ambiente (ENEA), gouvernement italien, Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), CERFACS, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques ( LOCEAN ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Departmento de Álgebra [Madrid] ( UCM ), Universidad Complutense de Madrid [Madrid] ( UCM ), Bjerknes Centre for Climate Research ( BCCR ), University of Bergen ( UIB ), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique ( CERFACS ), Groupe d'étude de l'atmosphère météorologique ( CNRM-GAME ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Météo France-Centre National de la Recherche Scientifique ( CNRS ), Centre de Recherches de Climatologie ( CRC ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), and Ente per le Nuove tecnologie, l'Energia e l'Ambiente ( ENEA )

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, interannual variability, Multidisciplinary analysis, [SDE.MCG]Environmental Sciences/Global Changes, Global warming, rainfall, 0207 environmental engineering, SST forced response, African Monsoon, 02 engineering and technology, Monsoon, 01 natural sciences, Sea surface temperature, West african, [ SDE.MCG ] Environmental Sciences/Global Changes, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Sahelian, Environmental science, [ SDU.STU.CL ] Sciences of the Universe [physics]/Earth Sciences/Climatology, 020701 environmental engineering, decadal variability, 0105 earth and related environmental sciences
Abstract

International audience; We review the studies carried out during the African Monsoon Multidisciplinary Analysis (AMMA)-EU on the changes of interannual sea surface temperature (SST)-West African monsoon (WAM) covariability at multidecadal timescales, together with the influence of global warming (GW). The results obtained in the AMMA-EU suggest the importance of the background state, modulated by natural and anthropogenic variability, in the appearance of different interannual modes. The lack of reliability of current coupled models in giving a realistic assessment for WAM in the future is also stated.

Published
2010
Full Text
View/download PDF

10. Impacts of Warm and Cold situations in the Mediterranean Basins on the West African monsoon: observed connection patterns (1979-2006) and climate simulations

Author

Sébastien Gervois, S. Sijikumar, Pascal Roucou, Paolo Ruti, Serge Janicot, Teresa Losada, Belén Rodríguez-Fonseca, Fabrice Chauvin, Javier García-Serrano, Bernard Fontaine, Centre de Recherches de Climatologie (CRC), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Ente per le Nuove tecnologie, l'Energia e l'Ambiente (ENEA), gouvernement italien, Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre de Recherches de Climatologie ( CRC ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Departmento de Álgebra [Madrid] ( UCM ), Universidad Complutense de Madrid [Madrid] ( UCM ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques ( LOCEAN ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Groupe d'étude de l'atmosphère météorologique ( CNRM-GAME ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Météo France-Centre National de la Recherche Scientifique ( CNRS ), and Ente per le Nuove tecnologie, l'Energia e l'Ambiente ( ENEA )

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Intertropical Convergence Zone, [SDE.MCG]Environmental Sciences/Global Changes, 0207 environmental engineering, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, Moisture advection, Monsoon, 01 natural sciences, Mediterranean Basin, [ SDE.MCG ] Environmental Sciences/Global Changes, Sea surface temperature, Mediterranean sea, [ PHYS.PHYS.PHYS-GEO-PH ] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Outgoing longwave radiation, [ SDU.STU.CL ] Sciences of the Universe [physics]/Earth Sciences/Climatology, 020701 environmental engineering, Geology, 0105 earth and related environmental sciences, Teleconnection
Abstract

International audience; Using both empirical and numerical ensemble approaches this study focuses on the Mediterranean / West African relationship in northern summer. Statistical analyses utilize skin temperature, sea surface temperature, in situ and satellite rainfall, Outgoing Longwave Radiation (OLR) observations and reanalyzed data winds and specific humidity on isobaric surfaces. Numerical investigations are based on a large set of sensitivity experiments performed on four Atmospheric General Circulation Models (AGCM): ARPEGE-Climat3, ECHAM4, LMDZ4 and UCLA7.3. Model outputs are compared to observations, discussed model by model and with an ensemble (multi-model) approach. As in previous studies the anomalous Mediterranean warm events are associated with specific impacts over the African monsoon region, i.e., a more intense monsoon, enhanced flux convergence and ascendances around the ITCZ, a strengthening of low level moisture advection and a more northward location of ascending motion in West Africa. The results show also new features (i) thermal variability observed in the two Mediterranean basins has unalike impacts, i.e. the western Mediterranean covaries with convection in Gulf of Guinea, while the eastern Mediterranean can be interpreted as Sahelian thermal-forcing; (ii) although observations show symmetry between warming and cooling, modelling evidences only support the eastern warming influence; (iii) anomalous East warm situations are associated with a more northward migration of the monsoon system accompanied by enhanced southwesterly flow and weakened northeasterly climatological wind; (iv) the multi-model response shows that anomalous East warm surface temperatures generate an enhancement of the overturning circulation in low and high levels, an increase in TEJ (Tropical Easterly Jet) and a decrease in AEJ (African Easterly Jet).

Published
2009
Full Text
View/download PDF

11. Multi-Harnack smoothings of real plane branches

Author

Pedro Daniel González Pérez, Jean-Jacques Risler, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut de Mathématiques de Jussieu (IMJ), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and González Pérez is supported by Programa Ramón y Cajal} and MTM2007-6798-C02-02 grants of Ministerio de Educación y Ciencia, Spain.

Subjects
Pure mathematics, 14H20, 14M25 (Secondary), General Mathematics, Harnack curves, Topology, Convex polygon, 01 natural sciences, Real plane, Mathematics - Algebraic Geometry, Singularity, Mathematics::Algebraic Geometry, 0103 physical sciences, FOS: Mathematics, real plane curves, Germ, Uniqueness, 0101 mathematics, Algebraic Geometry (math.AG), 14P25(Primary), Mathematics, 010102 general mathematics, smoothings of singularities, 16. Peace & justice, 2000 MSC Primary 14P25, Secondary 14H20 , 14M25, Geometria algebraica, 010307 mathematical physics, Algebraic curve, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], Locus (mathematics), Smoothing
Abstract

This paper is motivated by the results of G. Mikhalkin about a certain class of real algebraic curves, called Harnack curves, in toric surfaces. Mikhalkin has proved the existence of such curves as well as topological uniqueness of their real locus. The authors are concerned about an analogous statement in the case of a smoothing of a real plane branch (C, 0) _ (C2, 0) (an analytically irreducible germ of a real curve). They introduce the class of multi-Harnack smoothings of (C, 0) and prove its existence along with its topological uniqueness. Theorem 9.3. Any real plane branch (C, 0) has a multi-Harnack smoothing. Theorem 9.4. Let (C, 0) be a real branch. The topological type of multi-Harnack smoothings of (C, 0) is unique. There are at most two signed topological types of multi-Harnack smoothings of (C, 0). These types depend only on the sequence {(nj ,mj)}, which determines and is determined by the embedded topological type of (C, 0) _ (C2, 0). In terms of the parameters, multi-Harnack smoothings are multi-semi-quasi-homogeneous, which lets the authors analyze also the asymptotic multi-scales of the ovals.

Published
2008

12. Quasi Ordinary Singularities, Essential Divisors and Poincare Series

Author

Fernando Hernando, Pedro Daniel González Pérez, Departamento de Álgebra [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Dpto. Algebra, Geometría y Topología, Universidad de Valladolid [Valladolid] (UVa), and González Pérez is supported by Programa Ramón y Cajal and MTM2004-08080-C02-01 grants of MEC, Spain. Hernando is supported by grants MTM2004-010958 of MEC and VA068/04 of Junta de Castilla y León, Spain.

Subjects
Projectivization, quasi-ordinary singularities, Monomial, Pure mathematics, General Mathematics, 32S10, 14M25 (Secondary), 14J17 (Primary), Poincaré series, 01 natural sciences, toric singularities, Mathematics - Algebraic Geometry, symbols.namesake, Singularity, Mathematics::Algebraic Geometry, Euler characteristic, essential divisors, 0103 physical sciences, FOS: Mathematics, 0101 mathematics, Invariant (mathematics), Algebraic Geometry (math.AG), Mathematics, Mathematics::Commutative Algebra, 010102 general mathematics, 16. Peace & justice, Geometria algebraica, Hypersurface, 2000 Mathematics Subject Classification. Primary 14J17, Secondary 32S10, 14M25, symbols, Gravitational singularity, [MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG], 010307 mathematical physics
Abstract

We define Poincar\'e series associated to a toric or analytically irreducible quasi-ordinary hypersurface singularity, (S,0), by a finite sequence of monomial valuations, such that at least one of them is centered at the origin 0. This involves the definition of a multi-graded ring associated to the analytic algebra of the singularity by the sequence of valuations. We prove that the Poincar\'e series is a rational function with integer coefficients, which can be defined also as an integral with respect of the Euler characteristic, over the projectivization of the analytic algebra of the singularity, of a function defined by the valuations. In particular, the Poincar\'e series associated to the set of divisorial valuations associated to the essential divisors, considered both over the singular locus and over the point 0, is an analytic invariant of the singularity. In the quasi-ordinary hypersurface case we prove that this Poincar\'e series determines and it is determined by the normalized sequence of characteristic monomials. These monomials in the analytic case define a complete invariant of the embedded topological type of the hypersurface singularity., Comment: The version corrects some misprints

Published
2007
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results