Displaying 41 – 60 of 66

Showing per page

Théorèmes de structure sur certaines algèbres m-convexes commutatives.

Z. Abdelali, M. Chidami (2000)

Extracta Mathematicae

Nous donnons dans ce travail une caractérisation des algèbres (semi-simples) localement-convexes complètes faiblement topologisées au sens de S. Warner, ce qui clarifie, entre autres, plusiers résultats données sur certaines classes d'algèbres à base étudiées par de nombreux auteurs ([2], [6], [7]) pour approcher le problème de E. A. Michael sur la continuité des caractères dans les algèbres de Fréchet [9].

Topological algebras of random elements

Bertram M. Schreiber, M. Victoria Velasco (2016)

Studia Mathematica

Let L₀(Ω;A) be the Fréchet space of Bochner-measurable random variables with values in a unital complex Banach algebra A. We study L₀(Ω;A) as a topological algebra, investigating the notion of spectrum in L₀(Ω;A), the Jacobson radical, ideals, hulls and kernels. Several results on automatic continuity of homomorphisms are developed, including versions of well-known theorems of C. Rickart and B. E. Johnson.

Topological algebras with maximal regular ideals closed

Mati Abel (2012)

Open Mathematics

It is shown that all maximal regular ideals in a Hausdorff topological algebra A are closed if the von Neumann bornology of A has a pseudo-basis which consists of idempotent and completant absolutely pseudoconvex sets. Moreover, all ideals in a unital commutative sequentially Mackey complete Hausdorff topological algebra A with jointly continuous multiplication and bounded elements are closed if the von Neumann bornology of A is idempotently pseudoconvex.

Topological algebras with pseudoconvexly bounded elements

Mati Abel (2005)

Banach Center Publications

It is shown that every commutative sequentially bornologically complete Hausdorff algebra A with bounded elements is representable in the form of an (algebraic) inductive limit of an inductive system of locally bounded Fréchet algebras with continuous monomorphisms if the von Neumann bornology of A is pseudoconvex. Several classes of topological algebras A for which r A ( a ) β A ( a ) or r A ( a ) = β A ( a ) for each a ∈ A are described.

Topologically Invertible Elements and Topological Spectrum

Mati Abel, Wiesław Żelazko (2006)

Bulletin of the Polish Academy of Sciences. Mathematics

Properties of topologically invertible elements and the topological spectrum of elements in unital semitopological algebras are studied. It is shown that the inversion x x - 1 is continuous in every invertive Fréchet algebra, and singly generated unital semitopological algebras have continuous characters if and only if the topological spectrum of the generator is non-empty. Several open problems are presented.

Topologies of compact families on the ideal space of a Banach algebra

Ferdinand Beckhoff (1996)

Studia Mathematica

Let be a family of compact sets in a Banach algebra A such that is stable with respect to finite unions and contains all finite sets. Then the sets U ( K ) : = I I d ( A ) : I K = , K ∈ define a topology τ() on the space Id(A) of closed two-sided ideals of A. is called normal if I i I in (Id(A),τ()) and x ∈ A╲I imply l i m i n f i x + I i > 0 . (1) If the family of finite subsets of A is normal then Id(A) is locally compact in the hull kernel topology and if moreover A is separable then Id(A) is second countable. (2) If the family of countable compact sets...

Topologies on the space of ideals of a Banach algebra

Ferdinand Beckhoff (1995)

Studia Mathematica

Some topologies on the space Id(A) of two-sided and closed ideals of a Banach algebra are introduced and investigated. One of the topologies, namely τ , coincides with the so-called strong topology if A is a C*-algebra. We prove that for a separable Banach algebra τ coincides with a weaker topology when restricted to the space Min-Primal(A) of minimal closed primal ideals and that Min-Primal(A) is a Polish space if τ is Hausdorff; this generalizes results from [1] and [5]. All subspaces of Id(A)...

Currently displaying 41 – 60 of 66