Displaying 421 – 440 of 673

Showing per page

Spectral theory of SG pseudo-differential operators on L p ( )

Aparajita Dasgupta, M. W. Wong (2008)

Studia Mathematica

To every elliptic SG pseudo-differential operator with positive orders, we associate the minimal and maximal operators on L p ( ) , 1 < p < ∞, and prove that they are equal. The domain of the minimal ( = maximal) operator is explicitly computed in terms of a Sobolev space. We prove that an elliptic SG pseudo-differential operator is Fredholm. The essential spectra of elliptic SG pseudo-differential operators with positive orders and bounded SG pseudo-differential operators with orders 0,0 are computed....

Spectre du noyau intégral ( x 2 + y 2 + 1 ) - 1

Michel Gaudin (1981)

Annales de l'institut Fourier

On construit les fonctions propres sur R et les valeurs caractéristiques λ n du noyau de Hilbert-Schmidt ( x 2 + y 2 + 1 ) - 1 . Le spectre est donné par la solution d’une équation transcendante dont le comportement asymptotique est λ n 1 2 exp ( π n ) .

Strong and weak stability of some Markov operators

Ryszard Rudnicki (2000)

Colloquium Mathematicae

An integral Markov operator P appearing in biomathematics is investigated. This operator acts on the space of probabilistic Borel measures. Let μ and ν be probabilistic Borel measures. Sufficient conditions for weak and strong convergence of the sequence ( P n μ - P n ν ) to 0 are given.

Subalgebras to a Wiener type algebra of pseudo-differential operators

Joachim Toft (2001)

Annales de l’institut Fourier

We study general continuity properties for an increasing family of Banach spaces S w p of classes for pseudo-differential symbols, where S w = S w was introduced by J. Sjöstrand in 1993. We prove that the operators in Op ( S w p ) are Schatten-von Neumann operators of order p on L 2 . We prove also that Op ( S w p ) Op ( S w r ) Op ( S w r ) and S w p · S w q S w r , provided 1 / p + 1 / q = 1 / r . If instead 1 / p + 1 / q = 1 + 1 / r , then S w p w * S w q S w r . By modifying the definition of the S w p -spaces, one also obtains symbol classes related to the S ( m , g ) spaces.

Sur le spectre semi-classique d’un système intégrable de dimension 1 autour d’une singularité hyperbolique

Olivier Lablée (2007/2008)

Séminaire de théorie spectrale et géométrie

Dans cet article on décrit le spectre semi-classique d’un opérateur de Schrödinger sur avec un potentiel type double puits. La description qu’on donne est celle du spectre autour du maximum local du potentiel. Dans la classification des singularités de l’application moment d’un système intégrable, le double puits représente le cas des singularités non-dégénérées de type hyperbolique.

Currently displaying 421 – 440 of 673