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A Parseval equation and a generalized finite Hankel transformation

Jorge J. Betancor, Manuel T. Flores (1991)

Commentationes Mathematicae Universitatis Carolinae

In this paper, we study the finite Hankel transformation on spaces of generalized functions by developing a new procedure. We consider two Hankel type integral transformations h μ and h μ * connected by the Parseval equation n = 0 ( h μ f ) ( n ) ( h μ * ϕ ) ( n ) = 0 1 f ( x ) ϕ ( x ) d x . A space S μ of functions and a space L μ of complex sequences are introduced. h μ * is an isomorphism from S μ onto L μ when μ - 1 2 . We propose to define the generalized finite Hankel transform h μ ' f of f S μ ' by ( h μ ' f ) , ( ( h μ * ϕ ) ( n ) ) n = 0 = f , ϕ , for ϕ S μ .

A Pettis-type integral and applications to transition semigroups

Markus Kunze (2011)

Czechoslovak Mathematical Journal

Motivated by applications to transition semigroups, we introduce the notion of a norming dual pair and study a Pettis-type integral on such pairs. In particular, we establish a sufficient condition for integrability. We also introduce and study a class of semigroups on such dual pairs which are an abstract version of transition semigroups. Using our results, we give conditions ensuring that a semigroup consisting of kernel operators has a Laplace transform which also consists of kernel operators....

A Phragmén-Lindelöf type quasi-analyticity principle

Grzegorz Łysik (1997)

Studia Mathematica

Quasi-analyticity theorems of Phragmén-Lindelöf type for holomorphic functions of exponential type on a half plane are stated and proved. Spaces of Laplace distributions (ultradistributions) on ℝ are studied and their boundary value representation is given. A generalization of the Painlevé theorem is proved.

A priori estimates in geometry and Sobolev spaces on open manifolds

Jürgen Eichhorn (1992)

Banach Center Publications

Introduction. For bounded domains in R n satisfying the cone condition there are many embedding and module structure theorem for Sobolev spaces which are of great importance in solving partial differential equations. Unfortunately, most of them are wrong on arbitrary unbounded domains or on open manifolds. On the other hand, just these theorems play a decisive role in foundations of nonlinear analysis on open manifolds and in solving partial differential equations. This was pointed out by the author...

A probabilistic version of the Frequent Hypercyclicity Criterion

Sophie Grivaux (2006)

Studia Mathematica

For a bounded operator T on a separable infinite-dimensional Banach space X, we give a "random" criterion not involving ergodic theory which implies that T is frequently hypercyclic: there exists a vector x such that for every non-empty open subset U of X, the set of integers n such that Tⁿx belongs to U, has positive lower density. This gives a connection between two different methods for obtaining the frequent hypercyclicity of operators.

A product of three projections

Eva Kopecká, Vladimír Müller (2014)

Studia Mathematica

Let X and Y be two closed subspaces of a Hilbert space. If we send a point back and forth between them by orthogonal projections, the iterates converge to the projection of the point onto the intersection of X and Y by a theorem of von Neumann. Any sequence of orthoprojections of a point in a Hilbert space onto a finite family of closed subspaces converges weakly, according to Amemiya and Ando. The problem of norm convergence was open for a long time. Recently Adam Paszkiewicz...

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