Isoperimetry and symmetrization for Sobolev spaces on metric spaces

Using isoperimetry we obtain new symmetrization inequalities that allow us to provide a unified framework to study Sobolev inequalities in metric spaces. The applications include concentration inequalities, Poincaré inequalities, as well as metric versions of the Pólya–Szegö and Faber–Krahn principles. To cite this article: J. Martín, M. Milman, C. R. Acad. Sci. Paris, Ser. I 347 (2009).     

Sobolev's inequality for Riesz potentials with variable exponent satisfying a log-Hölder condition at infinity

Our aim in this paper is to deal with the boundedness of maximal functions in generalized Lebesgue spaces Lp(⋅) when p(⋅) satisfies a log-Hölder condition at infinity that is weaker than that of Cruz-Uribe, Fiorenza and Neugebauer [D. Cruz-Uribe, A. Fiorenza, C.J. Neugebauer, The maximal function on variable Lp spaces, Ann. Acad. Sci. Fenn. Math. 28 (2003) 223-238; 29 (2004) 247-249]. Our result extends the recent work of Diening [L. Diening, Maximal functions on generalized Lp(⋅) spaces, Math. Inequal. Appl. 7 (2004) 245-254] and the authors Futamura and Mizuta [T. Futamura, Y. Mizuta, Sobolev embeddings for Riesz potential space of variable exponent, preprint]. As an application of the boundedness of maximal functions, we show Sobolev's inequality for Riesz potentials with variable exponent.     

A semilinear non-classical pseudodifferential boundary value problem in the Sobolev spaces

We study the solvability of a semilinear non-classical pseudodifferential boundary value problem in the Sobolev spaces H_l,p,q, 1<p<∞, depending on a complex parameter q. To cite this article: Y.V. Egorov et al., C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

Eigenvalue problems in anisotropic Orlicz–Sobolev spaces

We establish sufficient conditions for the existence of solutions to a class of nonlinear eigenvalue problems involving nonhomogeneous differential operators in Orlicz–Sobolev spaces. To cite this article: M. Mih?ilescu et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009).     

Estimating the norm of conformal maps in Korenblum-Orlicz spaces

We use Young’s functions to define the Korenblum-Orlicz spaces as a generalization of the Korenblum spaces and we establish some of its properties. We show that the norm of the conformal maps in Korenblum-Orlicz spaces can be dominated by a certain expression involving the supremum over the inverse image of certain sectors. This extend a result of J. Ramos Fernández in (C. R. Math. Acad. Sci. Paris, 344(5):291–294, 2007) for α-Bloch spaces.     

Some characterizations of magnetic Sobolev spaces

ABSTRACT

The aim of this note is to survey recent results contained in Nguyen H-M, Squassina M. [On anisotropic Sobolev spaces. Commun Contemp Math, to appear. DOI:10.1142/S0219199718500177]; Nguyen H-M, Pinamonti A, Squassina M, et al. [New characterizations of magnetic Sobolev spaces. Adv Nonlinear Anal. 2018;7(2):227–245]; Pinamonti A, Squassina M, Vecchi E. [Magnetic BV functions and the Bourgain-Brezis-Mironescu formula. Adv Calc Var, to appear. DOI:10.1515/acv-2017-0019]; Pinamonti A, Squassina M, Vecchi E. [The Maz'ya-Shaposhnikova limit in the magnetic setting. J Math Anal Appl. 2017;449:1152–1159] and Squassina M, Volzone B. [Bourgain-Brezis-Mironescu formula for magnetic operators. C R Math Acad Sci Paris. 2016;354:825–831], where the authors extended to the magnetic setting several characterizations of Sobolev and BV functions.     

Various characterisations of Extended Chebyshev spaces via blossoms

Among all W-spaces (i.e. spaces with nonvanishing Wronskians), extended Cheyshev spaces can be characterised by the existence of either Bernstein bases, or B-spline bases, or Bézier points, or blossoms in the spaces obtained by integration. To cite this article: M.-L. Mazure, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

Sharp Hodge decompositions in two and three dimensional Lipschitz domainsDécompositions de Hodge optimales pour les domaines lipschitziens en dimensions deux et trois

We identify the optimal range of coefficients s, p for which differential forms with coefficients in the Sobolev space $\text{L}{}^{\mathrm{p}}{}_{\mathrm{s}}\text{(Ω)}$ admit natural Hodge decompositions in arbitrary two and three dimensional Lipschitz domains $\text{Ω}$. To cite this article: D. Mitrea, M. Mitrea, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 109–112     

Petits espaces de Lebesgue et quelques applicationsOn small Lebesgue spaces and their applications

We prove some new properties of the small Lebesgue spaces introduced by Fiorenza [7]. Combining these properties with the Poincaré–Sobolev inequalities for the relative rearrangement (see [11]), we derive some new and precises estimates either for small Lebesgue–Sobolev spaces or for quasilinear equations with data in the small Lebesgue spaces. To cite this article: A. Fiorenza, J.-M. Rakotoson, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 23–26     

Cameron-Martin formula for the σ-finite measure unifying Brownian penalisations

Quasi-invariance under translation is established for the σ-finite measure unifying Brownian penalisations, which has been introduced by Najnudel, Roynette and Yor [J. Najnudel, B. Roynette, M. Yor, A remarkable σ-finite measure on C(R₊,R) related to many Brownian penalisations, C. R. Math. Acad. Sci. Paris 345 (8) (2007) 459-466]. For this purpose, the theory of Wiener integrals for centered Bessel processes, due to Funaki, Hariya and Yor [T. Funaki, Y. Hariya, M. Yor, Wiener integrals for centered Bessel and related processes. II, ALEA Lat. Am. J. Probab. Math. Stat. 1 (2006) 225-240 (electronic)], plays a key role.     

On period spaces for p-divisible groups

In their book Rapoport and Zink constructed rigid analytic period spaces for Fontaine's filtered isocrystals, and period morphisms from moduli spaces of p-divisible groups to some of these period spaces. We determine the image of these period morphisms, thereby contributing to a question of Grothendieck. We give examples showing that only in rare cases the image is all of the Rapoport–Zink period space. To cite this article: U. Hartl, C. R. Acad. Sci. Paris, Ser. I 346 (2008).     

Mixed exterior Laplace's problem

In [C. Amrouche, V. Girault, J. Giroire, Dirichlet and Neumann exterior problems for the n-dimensional Laplace operator. An approach in weighted Sobolev spaces, J. Math. Pures Appl. 76 (1997) 55-81], authors study Dirichlet and Neumann problems for the Laplace operator in exterior domains of Rn. This paper extends this study to the resolution of a mixed exterior Laplace's problem. Here, we give existence, unicity and regularity results in Lp's theory with 1<p<∞, in weighted Sobolev spaces.     

The Neumann problem in the half-spaceLe problème de Neumannn dans le demi-espace

We study here the nonhomogeneous Neumann problem in the half-space $\text{R}{}^{\mathrm{N}}{}_{\mathrm{+}}$ with N?2. We give in L^p theory, with 1<p<∞, a basic existence and regularity results in weighted Sobolev spaces. To cite this article: C. Amrouche, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 151–156.     

Sharp weighted Hardy type inequalities and Hardy–Sobolev type inequalities on polarizable Carnot groups

In this Note, we establish sharp weighted Hardy type inequalities with a more general index p on polarizable Carnot groups, which include Kombe's recent results; then a weighted Hardy–Sobolev type inequality is obtained by using previous inequalities. To cite this article: J. Wang, P. Niu, C. R. Acad. Sci. Paris, Ser. I 346 (2008).     

Cohomologie des espaces symétriques de Drinfeld et cocycles harmoniques

We show that the cohomology groups of the Drinfeld symmetric space $\text{Ω}{}^{\mathrm{(n+1)}}$ defined over a local field of any characteristic are GL_n+1-isomorphic to certain spaces of harmonic cochains on the Bruhat–Tits building. To cite this article: Y. Aït Amrane, C. R. Acad. Sci. Paris, Ser. I 338 (2004).     

A Note on Kato–Nakayama spaces

In this Note we prove the following result. A fine log scheme over the complex numbers and its saturated have homeomorphic Kato–Nakayama associated spaces. Moreover these spaces are isomorphic as ringed spaces, either with the ring sheaf defined by Kato–Nakayama, or with that defined by Ogus. In the definition of these spaces, non-integral monoids are involved, so that the proof of the result is based on properties of nonnecessarily integral monoids. To cite this article: M. Cailotto, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

Applications aux sommes elliptiques d'Apostol–Dedekind–Zagier

In this Note, we give two applications to our work [Bayad, C. R. Acad. Sci. Paris, Ser. I 339 (2004); DOI: 10.1016/j.crma.2004.07.018] concerning multiple elliptic Apostol–Dedekind–Zagier sums. These elliptic sums are defined by means of certain Jacobi modular forms of two variables $D_{\tau }(z\text{;}\phi )$. When $\text{Im}(\tau )\to \infty$, these elliptic sums give the classical Apostol–Dedekind–Zagier multiple sums [Apostol, Duke Math. J. 17 (1950) 147–157, Pacific. J. Math 2 (1952) 1–9; Zagier, Math. Ann, 202 (1973) 149–172]. We give a reciprocity law for these sums. To cite this article: A. Bayad, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

On the recovery of a curve isometrically immersed in a Euclidean space

It is known from differential geometry that one can reconstruct a curve with n?1 prescribed curvature functions, if these functions can be differentiated a certain number of times in the usual sense and if the first n?2 functions are strictly positive. We establish here that this result still holds under the assumption that the curvature functions belong to some Sobolev spaces, by using the notion of derivative in the distributional sense. We also show that the mapping that associates with such prescribed curvature functions the reconstructed curve is of class $\text{C}{}^{\mathrm{\infty }}$. To cite this article: M. Szopos, C. R. Acad. Sci. Paris, Ser. I 338 (2004).