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On the complexity of Hamel bases of infinite-dimensional Banach spaces

Lorenz Halbeisen (2001)

Colloquium Mathematicae

We call a subset S of a topological vector space V linearly Borel if for every finite number n, the set of all linear combinations of S of length n is a Borel subset of V. It is shown that a Hamel basis of an infinite-dimensional Banach space can never be linearly Borel. This answers a question of Anatoliĭ Plichko.

On the complexity of some classes of Banach spaces and non-universality

Bruno M. Braga (2014)

Czechoslovak Mathematical Journal

These notes are dedicated to the study of the complexity of several classes of separable Banach spaces. We compute the complexity of the Banach-Saks property, the alternating Banach-Saks property, the complete continuous property, and the LUST property. We also show that the weak Banach-Saks property, the Schur property, the Dunford-Pettis property, the analytic Radon-Nikodym property, the set of Banach spaces whose set of unconditionally converging operators is complemented in its bounded operators,...

On the Composition Operator in AC[a,b].

Nelson Merentes (1991)

Collectanea Mathematica

Denote by F the composition operator generated by a given function f: R --> R, acting on the space of absolutely continuous functions. In this paper we prove that the composition operator F maps the space AC[a,b] into itself if and only if f satisfies a local Lipschitz condition on R.

On the continuity of Bessel potentials in Orlicz spaces.

N. Aïssaoui (1996)

Collectanea Mathematica

It is shown that Bessel capacities in reflexive Orlicz spaces are non increasing under orthogonal projection of sets. This is used to get a continuity of potentials on some subspaces. The obtained results generalize those of Meyers and Reshetnyak in the case of Lebesgue classes.

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