Displaying similar documents to “Idéaux fermés de certaines algèbres de Beurling et application aux opérateurs à spectre dénombrable”

Sur les courbes hyperelliptiques cyclotomiques et les équations x p - y p = c z ²

Wilfrid Ivorra

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Let p be a prime number ≥ 11 and c be a square-free integer ≥ 3. In this paper, we study the diophantine equation x p - y p = c z ² in the case where p belongs to 11,13,17. More precisely, we prove that for those primes, there is no integer solution (x,y,z) to this equation satisfying gcd(x,y,z) = 1 and xyz ≠ 0 if the integer c has the following property: if ℓ is a prime number dividing c then ℓ ≢ 1 mod p. To obtain this result, we consider the hyperelliptic curves C p : y ² = Φ p ( x ) and D p : p y ² = Φ p ( x ) , where Φ p is the pth cyclotomic...

Sur un problème de Rényi et Ivić concernant les fonctions de diviseurs de Piltz

Rimer Zurita (2013)

Acta Arithmetica

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Let Ω(n) and ω(n) denote the number of distinct prime factors of the positive integer n, counted respectively with and without multiplicity. Let d k ( n ) denote the Piltz function (which counts the number of ways of writing n as a product of k factors). We obtain a precise estimate of the sum n x , Ω ( n ) - ω ( n ) = q f ( n ) for a class of multiplicative functions f, including in particular f ( n ) = d k ( n ) , unconditionally if 1 ≤ k ≤ 3, and under some reasonable assumptions if k ≥ 4. The result also applies to f(n) = φ(n)/n (where φ is...

Présentation jordanienne de l'algèbre de Weyl A₂

J. Alev, F. Dumas (2001)

Annales Polonici Mathematici

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Let k be a commutative field. For any a,b∈ k, we denote by J a , b ( k ) the deformation of the 2-dimensional Weyl algebra over k associated with the Jordanian Hecke symmetry with parameters a and b. We prove that: (i) any J a , b ( k ) can be embedded in the usual Weyl algebra A₂(k), and (ii) J a , b ( k ) is isomorphic to A₂(k) if and only if a = b.

Une formule pour les extensions de foncteurs composés

Alain Troesch (2003)

Fundamenta Mathematicae

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Let p be a prime, and let ℱ be the category of functors from the finite p -vector spaces to all p -vector spaces. The object Id of ℱ is the inclusion functor. Let F and G be two objects in ℱ. If F and G satisfy suitable conditions, the main result of this paper allows one to compute E x t * ( I d , G F ) from the knowledge of E x t * ( I d , F ) and E x t * ( I d , G ) .

Fonctions maximales centrées de Hardy-Littlewood sur les groupes de Heisenberg

Hong-Quan Li (2009)

Studia Mathematica

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By getting uniformly asymptotic estimates for the Poisson kernel on Heisenberg groups 2 n + 1 , we prove that there exists a constant A > 0, independent of n ∈ ℕ*, such that for all f L ¹ ( 2 n + 1 ) , we have | | M f | | L 1 , A n | | f | | , where M denotes the centered Hardy-Littlewood maximal function defined by the Carnot-Carathéodory distance or by the Korányi norm.

Espaces BMO, inégalités de Paley et multiplicateurs idempotents

Hubert Lelièvre (1997)

Studia Mathematica

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Generalizing the classical BMO spaces defined on the unit circle with vector or scalar values, we define the spaces B M O ψ q ( ) and B M O ψ q ( , B ) , where ψ q ( x ) = e x q - 1 for x ≥ 0 and q ∈ [1,∞[, and where B is a Banach space. Note that B M O ψ 1 ( ) = B M O ( ) and B M O ψ 1 ( , B ) = B M O ( , B ) by the John-Nirenberg theorem. Firstly, we study a generalization of the classical Paley inequality and improve the Blasco-Pełczyński theorem in the vector case. Secondly, we compute the idempotent multipliers of B M O ψ q ( ) . Pisier conjectured that the supports of idempotent multipliers of...

Inégalités à poids pour l'opérateur de Hardy-Littlewood-Sobolev dans les espaces métriques mesurés à deux demi-dimensions

David Mascré (2006)

Colloquium Mathematicae

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On a metric measure space (X,ϱ,μ), consider the weight functions w α ( x ) = ϱ ( x , z ) - α if ϱ(x,z₀) < 1, w α ( x ) = ϱ ( x , z ) - α if ϱ(x,z₀) ≥ 1, w β ( x ) = ϱ ( x , z ) - β if ϱ(x,z₀) < 1, w β ( x ) = ϱ ( x , z ) - β if ϱ(x,z₀) ≥ 1, where z₀ is a given point of X, and let κ a : X × X be an operator kernel satisfying κ a ( x , y ) c ϱ ( x , y ) a - d for all x,y ∈ X such that ϱ(x,y) < 1, κ a ( x , y ) c ϱ ( x , y ) a - D for all x,y ∈ X such that ϱ(x,y)≥ 1, where 0 < a < min(d,D), and d and D are respectively the local and global volume growth rate of the space X. We determine conditions on a, α₀, α₁, β₀, β₁ ∈ ℝ for the Hardy-Littlewood-Sobolev...

L p ( G , X * ) comme sous-espace complémenté de L q ( G , X ) *

Mohammad Daher (2013)

Colloquium Mathematicae

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Let G be a compact metric infinite abelian group and let X be a Banach space. We study the following question: if the dual X* of X does not have the Radon-Nikodym property, is L p ( G , X * ) complemented in L q ( G , X ) * , 1 < p ≤ ∞, 1/p + 1/q = 1, or, if p = 1, in the subspace of C(G,X)* consisting of the measures that are absolutely continuous with respect to the Haar measure? We show that the answer is negative if X is separable and does not contain ℓ¹, and if 1 ≤ p < ∞. If p = 1, this answers a question...

Feuilletages holomorphes de codimension un dont la classe canonique est triviale

Frédéric Touzet (2008)

Annales scientifiques de l'École Normale Supérieure

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We give a description of Kähler manifolds M equipped with an integrable subbundle of T M of rank n - 1 ( n = dim M ) under the assumption that the line bundle D é t is numerically trivial. This is a sort of foliated version of Bogomolov’s theorem concerning Kähler manifolds with trivial canonical class.

Les -types du système

K. Nour (2010)

RAIRO - Theoretical Informatics and Applications

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We prove in this paper that the types of system inhabited uniquely by λ-terms (the -types) have a positive quantifier. We give also consequences of this result and some examples.

Derivees tangentielles des fonctions de la classe k , α dans les domaines de type fini de ℂ²

Laurent Verdoucq (2002)

Annales Polonici Mathematici

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Let Ω be a domain of finite type in ℂ² and let f be a function holomorphic in Ω and belonging to k , α ( Ω ̅ ) . We prove the existence of boundary values for some suitable derivatives of f of order greater than k. The gain of derivatives holds in the complex-tangential direction and it is precisely related to the geometry of ∂Ω. Then we prove a property of non-isotropic Hölder regularity for these boundary values. This generalizes some results given by J. Bruna and J. M. Ortega for the unit ball. ...

Sur un problème parabolique-elliptique

Philippe Benilan, Petra Wittbold (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

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We prove existence (uniqueness is easy) of a weak solution to a boundary value problem for an equation like ( v - 1 ) t + = v x x + F ( v ) x where the function F : is only supposed to be locally lipschitz continuous. In order to replace the lack of compactness in on , we use nonlinear semigroup theory.

Stabilité L 1 d’ondes progressives de lois de conservation scalaires

Denis Serre (1998-1999)

Séminaire Équations aux dérivées partielles

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A powerfull method has been developped in [2] for the study of L 1 -stability of travelling waves in conservation laws or more generally in equations which display L 1 -contractivity, maximum principle and mass conservation. We recall shortly the general procedure. We also show that it partly applies to the waves of a model of radiating gas. These waves have first been studied by Kawashima and Nishibata [5,6] in a different framework. Therefore, shock fronts for this model are stable under...

Sous-groupes H -loxodromiques

Antonin Guilloux (2011)

Bulletin de la Société Mathématique de France

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On considère une extension finie k de p , avec p un nombre premier, H un sous-groupe d’indice fini de k * et le groupe SL ( n , k ) . Nous montrons que SL ( n , k ) admet un sous-groupe p -Zariski-dense dont toutes les matrices ont leur spectre inclus dans H si et seulement si soit - 1 est dans le sous-groupe H , soit n n’est pas congru à 2 modulo 4.

Système de processus auto-stabilisants

Samuel Herrmann

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Taking an odd increasing Lipschitz-continuous function with polynomial growth β, an odd Lipschitz-continuous and bounded function ϕ satisfying sgn(x)ϕ(x) ≥ 0 and a parameter a ∈ [1/2,1], we consider the (nonlinear) stochastic differential system ⎧ X t = X + B t + a 0 t ϕ * v s ( X s ) d s - ( 1 - a ) 0 t β * u s ( X s ) d s , (E)⎨ ⎩ Y t = Y + B ̃ t + ( 1 - a ) 0 t ϕ * u s ( Y s ) d s - a 0 t β * v s ( Y s ) d s , ( X t d x ) = u t ( d x ) and ( Y t d x ) = v t ( d x ) , where β * u t ( x ) = β ( x - y ) u t ( d y ) , ( B t ) t 0 and ( B ̃ t ) t 0 are independent Brownian motions. We show that (E) admits a stationary probability measure, and, under some additional conditions, that ( X t , Y t ) converges in distribution to this invariant measure. Moreover we...

Propriétés (Q) et (C). Variété commutante

Jean-Yves Charbonnel (2004)

Bulletin de la Société Mathématique de France

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Soient X une variété algébrique complexe, lisse, irréductible, E et F deux espaces vectoriels complexes de dimension finie et μ un morphisme de X dans l’espace Lin ( E , F ) des applications linéaires de E dans F . Pour x X , on note E ( x ) et x · E le noyau et l’image de μ ( x ) , μ ¯ x le morphisme de X dans Lin ( E ( x ) , F / ( x · E ) ) qui associe à y l’application linéaire v μ ( y ) ( v ) + x · E . Soit i μ la dimension minimale de E ( x ) . On dit que μ asi i μ ¯ x est inférieur à i μ . Soient F * le dual de F , S ( F ) l’algèbre symétrique de F , μ l’idéal de 𝒪 X S ( F ) engendré par les fonctions...