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On generalized topological spaces I

Artur Piękosz (2013)

Annales Polonici Mathematici

We begin a systematic study of the category GTS of generalized topological spaces (in the sense of H. Delfs and M. Knebusch) and their strictly continuous mappings. We reformulate the axioms. Generalized topology is found to be connected with the concept of a bornological universe. Both GTS and its full subcategory SS of small spaces are topological categories. The second part of this paper will also appear in this journal.

On generalized topological spaces II

Artur Piękosz (2013)

Annales Polonici Mathematici

This is the second part of A. Piękosz [Ann. Polon. Math. 107 (2013), 217-241]. The categories GTS(M), with M a non-empty set, are shown to be topological. Several related categories are proved to be finitely complete. Locally small and nice weakly small spaces can be described using certain sublattices of power sets. Some important elements of the theory of locally definable and weakly definable spaces are reconstructed in a wide context of structures with topologies.

On group representations whose C * algebra is an ideal in its von Neumann algebra

Edmond E. Granirer (1979)

Annales de l'institut Fourier

Let τ be a continuous unitary representation of the locally compact group G on the Hilbert space H τ . Let C τ * [ V N τ ] be the C * [ W * ] algebra generated by ( L 1 ( G ) ) and M τ ( C τ * ) = φ V N τ ; φ C τ * + C τ * φ C τ * . The main result obtained in this paper is Theorem 1:If G is σ -compact and M τ ( C τ * ) = V N τ then supp τ is discrete and each π in supp τ in CCR.We apply this theorem to the quasiregular representation τ = π H and obtain among other results that M π H ( C π H * ) = V N π H implies in many cases that G / H is a compact coset space.

On Hamel bases in Banach spaces

Juan Carlos Ferrando (2014)

Studia Mathematica

It is shown that no infinite-dimensional Banach space can have a weakly K-analytic Hamel basis. As consequences, (i) no infinite-dimensional weakly analytic separable Banach space E has a Hamel basis C-embedded in E(weak), and (ii) no infinite-dimensional Banach space has a weakly pseudocompact Hamel basis. Among other results, it is also shown that there exist noncomplete normed barrelled spaces with closed discrete Hamel bases of arbitrarily large cardinality.

On Hankel transform and Hankel convolution of Beurling type distributions having upper bounded support

M. Belhadj, Jorge J. Betancor (2004)

Czechoslovak Mathematical Journal

In this paper we study Beurling type distributions in the Hankel setting. We consider the space ( w ) ' of Beurling type distributions on ( 0 , ) having upper bounded support. The Hankel transform and the Hankel convolution are studied on the space ( w ) ' . We also establish Paley Wiener type theorems for Hankel transformations of distributions in ( w ) ' .

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