Displaying similar documents to “Transition operators on co-compact G-spaces.”

Explicit spectral gap estimates for the linearized Boltzmann and Landau operators with hard potentials.

Céline Baranger, Clément Mouhot (2005)

Revista Matemática Iberoamericana

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This paper deals with explicit spectral gap estimates for the linearized Boltzmann operator with hard potentials (and hard spheres). We prove that it can be reduced to the Maxwellian case, for which explicit estimates are already known. Such a method is constructive, does not rely on Weyl's Theorem and thus does not require Grad's splitting. The more physical idea of the proof is to use geometrical properties of the whole collision operator. In a second part, we use the fact that the...

SAK principle for a class of Grushin-type operators.

Lidia Maniccia, Marco Mughetti (2006)

Revista Matemática Iberoamericana

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We prove Fefferman's SAK Principle for a class of hypoelliptic operators on R whose nonnegative symbol vanishes anisotropically on the characteristic manifold.

Some non-linear function theoretic properties of Riemannian manifolds.

Stefano Pigola, Marco Rigoli, Alberto G. Setti (2006)

Revista Matemática Iberoamericana

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We study the appropriate versions of parabolicity stochastic completeness and related Liouville properties for a general class of operators which include the p-Laplace operator, and the non linear singular operators in non-diagonal form considered by J. Serrin and collaborators.

Superposition operators and functions of bounded p-variation.

Gérard Bourdaud, Massimo Lanza de Cristoforis, Winfried Sickel (2006)

Revista Matemática Iberoamericana

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We characterize the set of all functions f of R to itself such that the associated superposition operator T: g → f º g maps the class BV (R) into itself. Here BV (R), 1 ≤ p < ∞, denotes the set of primitives of functions of bounded p-variation, endowed with a suitable norm. It turns out that such an operator is always bounded and sublinear. Also, consequences for the boundedness of superposition operators defined on Besov spaces B ...

Time-frequency analysis of Sjöstrand's class.

Karlheinz Gröchenig (2006)

Revista Matemática Iberoamericana

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We investigate the properties an exotic symbol class of pseudodifferential operators, Sjöstrand's class, with methods of time-frequency analysis (phase space analysis). Compared to the classical treatment, the time-frequency approach leads to striklingly simple proofs of Sjöstrand's fundamental results and to far-reaching generalizations.

Algebro-geometric solutions of the Camassa-Holm hierarchy.

Fritz Gesztesy, Helge Holden (2003)

Revista Matemática Iberoamericana

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We provide a detailed treatment of the Camassa-Holm (CH) hierarchy with special emphasis on its algebro-geometric solutions. In analogy to other completely integrable hierarchies of soliton equations such as the KdV or AKNS hierarchies, the CH hierarchy is recursively constructed by means of a basic polynomial formalism invoking a spectral parameter. Moreover, we study Dubrovin-type equations for auxiliary divisors and associated trace formulas, consider the corresponding algebro-geometric...

A uniform estimate for quartile operators.

Christoph Thiele (2002)

Revista Matemática Iberoamericana

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There is a one parameter family of bilinear Hilbert transforms. Recently, some progress has been made to prove Lp estimates for these operators uniformly in the parameter. In the current article we present some of these techniques in a simplified model...