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Interactions de singularités pour une classe d'équations à caractéristiques doubles

Eric Leichtnam (1985)

Annales de l'institut Fourier

Nous précisons, dans le contexte microlocal Sobolev, les résultats de propagations de singularités obtenus par N. Hanges dans le contexte microlocal C pour les opérateurs pseudo-differentiels à symbole principal réel et dont la variété caractéristique est la réunion de deux hypersurfaces lisses d’intersection non involutive. Nous obtenons également un résultat de propagation dans un cas non linéaire. Nos démonstrations consistent essentiellement à étudier l’action des paramétrices constantes par...

K-theory of Boutet de Monvel's algebra

Severino T. Melo, Ryszard Nest, Elmar Schrohe (2003)

Banach Center Publications

We consider the norm closure 𝔄 of the algebra of all operators of order and class zero in Boutet de Monvel's calculus on a compact manifold X with boundary ∂X. Assuming that all connected components of X have nonempty boundary, we show that K₁(𝔄) ≃ K₁(C(X)) ⊕ ker χ, where χ: K₀(C₀(T*Ẋ)) → ℤ is the topological index, T*Ẋ denoting the cotangent bundle of the interior. Also K₀(𝔄) is topologically determined. In case ∂X has torsion free K-theory, we get K₀(𝔄) ≃ K₀(C(X)) ⊕ K₁(C₀(T*Ẋ)).

L p -boundedness for pseudodifferential operators with non-smooth symbols and applications

Gianluca Garello, Alessandro Morando (2005)

Bollettino dell'Unione Matematica Italiana

Starting from a general formulation of the characterization by dyadic crowns of Sobolev spaces, the authors give a result of L p continuity for pseudodifferential operators whose symbol a(x,ξ) is non smooth with respect to x and whose derivatives with respect to ξ have a decay of order ρ with 0 < ρ 1 . The algebra property for some classes of weighted Sobolev spaces is proved and an application to multi - quasi - elliptic semilinear equations is given.

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