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The kh-socle of a commutative semisimple Banach algebra

Youness Hadder (2020)

Mathematica Bohemica

Let 𝒜 be a commutative complex semisimple Banach algebra. Denote by kh ( soc ( 𝒜 ) ) the kernel of the hull of the socle of 𝒜 . In this work we give some new characterizations of this ideal in terms of minimal idempotents in 𝒜 . This allows us to show that a “result” from Riesz theory in commutative Banach algebras is not true.

The norm spectrum in certain classes of commutative Banach algebras

H. S. Mustafayev (2011)

Colloquium Mathematicae

Let A be a commutative Banach algebra and let Σ A be its structure space. The norm spectrum σ(f) of the functional f ∈ A* is defined by σ ( f ) = f · a : a A ¯ Σ A , where f·a is the functional on A defined by ⟨f·a,b⟩ = ⟨f,ab⟩, b ∈ A. We investigate basic properties of the norm spectrum in certain classes of commutative Banach algebras and present some applications.

The Słodkowski spectra and higher Shilov boundaries

Vladimír Müller (1993)

Studia Mathematica

We investigate relations between the spectra defined by Słodkowski [14] and higher Shilov boundaries of the Taylor spectrum. The results generalize the well-known relation between the approximate point spectrum and the usual Shilov boundary.

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)...

Trivial generators for nontrivial fibres

Linus Carlsson (2008)

Mathematica Bohemica

Pseudoconvex domains are exhausted in such a way that we keep a part of the boundary fixed in all the domains of the exhaustion. This is used to solve a problem concerning whether the generators for the ideal of either the holomorphic functions continuous up to the boundary or the bounded holomorphic functions, vanishing at a point in n where the fibre is nontrivial, has to exceed n . This is shown not to be the case.

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