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Some results on elliptic and parabolic equations in Hilbert spaces

Giuseppe Da Prato (1996)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

We consider elliptic and parabolic equations with infinitely many variables. We prove some results of existence, uniqueness and regularity of solutions.

Some spectral properties of the streaming operator with general boundary conditions

Mohamed Boulanouar (2008)

Applications of Mathematics

This paper deals with the spectral study of the streaming operator with general boundary conditions defined by means of a boundary operator K . We study the positivity and the irreducibility of the generated semigroup proved in [M. Boulanouar, L’opérateur d’Advection: existence d’un C 0 -semi-groupe (I), Transp. Theory Stat. Phys. 31, 2002, 153–167], in the case K 1 . We also give some spectral properties of the streaming operator and we characterize the type of the generated semigroup in terms of the...

Some Tauberian theorems related to operator theory

C. Batty (1994)

Banach Center Publications

This article is a survey of some Tauberian theorems obtained recently in connection with work on asymptotic behaviour of semigroups of operators on Banach spaces. The results in operator theory are described in [6], where we made little attempt to show the Tauberian aspects. At the end of this article, we will give a sketch of the connections between the results in this article and in [6]; for details, the reader can turn to the original papers. In this article, we make no attempt to describe...

Sottospazi invarianti per operatori lineari T-invarianti rispetto ad un gruppo di omeomorfismi

Lucilla Bassotti Rizza (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Theory of T -invariant linear operators which was considered for a group of congruences [2], [3] is now extended to a group of homeomorphisms. An analysis is carried out in order to establish to what extent the main results of the previous theory still hold under the actual very general assumptions.

Spectral gap lower bound for the one-dimensional fractional Schrödinger operator in the interval

Kamil Kaleta (2012)

Studia Mathematica

We prove a uniform lower bound for the difference λ₂ - λ₁ between the first two eigenvalues of the fractional Schrödinger operator ( - Δ ) α / 2 + V , α ∈ (1,2), with a symmetric single-well potential V in a bounded interval (a,b), which is related to the Feynman-Kac semigroup of the symmetric α-stable process killed upon leaving (a,b). “Uniform” means that the positive constant C α appearing in our estimate λ - λ C α ( b - a ) - α is independent of the potential V. In the general case of α ∈ (0,2), we also find a uniform lower bound for...

Spectral properties of weakly almost periodic cosine functions

Valentina Casarino (1998)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

The spectral structure of the infinitesimal generator of a strongly continuous cosine function of linear bounded operators is investigated, under assumptions on the almost periodic behaviour of applications generated, in various ways, by C. Moreover, a first approach is presented to the analysis of connection between cosine functions and dynamical systems.

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