Displaying similar documents to “La notion de fermé dans un espace de Spanier.”

Faisceaux cohérents sur les courbes multiples.

Jean-Marc Drézet (2006)

Collectanea Mathematica

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This paper is devoted to the study of coherent sheaves on non reduced curves that can be locally embedded in smooth surfaces. If Y is such a curve then there is a filtration C ⊂ C ⊂ ... ⊂ C = Y such that C is the reduced curve associated to Y, and for very P ∈ C there exists z ∈ O such that (z) is the ideal of C in O. We define, using canonical filtrations, new invariants of coherent sheaves on Y: the and , and use them to state a for sheaves on Y. We define , which are locally isomorphic...

Recouvrements, derivation des mesures et dimensions.

Patrice Assouad, Thierry Quentin de Gromard (2006)

Revista Matemática Iberoamericana

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Let X be a set with a symmetric kernel d (not necessarily a distance). The space (X,d) is said to have the weak (resp. strong) covering property of degree ≤ m [briefly prf(m) (resp. prF(m))], if, for each family B of closed balls of (X,d) with radii in a decreasing sequence (resp. with bounded radii), there is a subfamily, covering the center of each element of B, and of order ≤ m (resp. splitting into m disjoint families). Since Besicovitch,...

Sur l'intersection des courants laminaires.

Romain Dujardin (2004)

Publicacions Matemàtiques

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We try to find a geometric interpretation of the wedge product of positive closed laminar currents in C2. We say such a wedge product is geometric if it is given by intersecting the disks filling up the currents. Uniformly laminar currents do always intersect geometrically in this sense. We also introduce a class of strongly approximable laminar currents, natural from the dynamical point of view, and prove that such currents intersect geometrically provided they have continuous potentials. ...

Déformation localisée de surfaces de Riemann.

Peter Haïssinsky (2005)

Publicacions Matemàtiques

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Let Y be a Riemann surface with compact boundary embedded into a hyperbolic Riemann surface of finite type X. It is proved that the space of deformations D of Y into X is an open subset of the Teichmüller space T(X) of X. Furthermore, D has compact closure if and only if Y is simply connected or isomorphic to a punctured disk, and D= T(X) if and only if the components of X Y are all disks or punctured disks.

Sur l'irréductibilité dans l'anneau des séries de Dirichlet analytiques.

Frédéric Bayart, Augustin Mouze (2005)

Publicacions Matemàtiques

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We discuss some local analytic properties of the ring of Dirichlet series. We obtain mainly the equivalence between the irreducibility in the analytic ring and in the formal one. In the same way we prove that the ring of analytic Dirichlet series is integrally closed in the ring of formal Dirichlet series. Finally we introduce the notion of standard basis in these rings and we give a finitely generated ideal which does not admit standard bases.

Poches de tourbillon singulières dans un fluide faiblement visqueux.

Taoufik Hmidi (2006)

Revista Matemática Iberoamericana

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In this paper, we study the singular vortex patches in the two-dimensional incompressible Navier-Stokes equations. We show, in particular, that if the initial vortex patch is C outside a singular set Σ, so the velocity is, for all time, lipschitzian outside the image of Σ through the viscous flow. In addition, the correponding lipschitzian norm is independent of the viscosity. This allows us to prove some results related to the inviscid limit for the geometric structures of the vortex...

Équation anisotrope de Navier-Stokes dans des espaces critiques.

Marius Paicu (2005)

Revista Matemática Iberoamericana

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We study the tridimensional Navier-Stokes equation when the value of the vertical viscosity is zero, in a critical space (invariant by the scaling). We shall prove local in time existence of the solution, respectively global in time when the initial data is small compared with the horizontal viscosity.

Réseaux modulaires à structure variable

Louise Martin (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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Si dà una formalizzazione dei moduli e delle reti modulari a struttura variabile. Si dimostra che per ogni automa finito a struttura variabile esiste una rete modulare a struttura variabile che lo simula. Si stabilisce il legame tra un automa a struttura variabile e l'automa a struttura variabile associato a una rete modulare a struttura variabile che lo simula.

Réseaux modulaires à structure variable

Louise Martin (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Similarity:

Si dà una formalizzazione dei moduli e delle reti modulari a struttura variabile. Si dimostra che per ogni automa finito a struttura variabile esiste una rete modulare a struttura variabile che lo simula. Si stabilisce il legame tra un automa a struttura variabile e l'automa a struttura variabile associato a una rete modulare a struttura variabile che lo simula.