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Rearrangement of series in nonnuclear spaces

Wojciech Banaszczyk (1993)

Studia Mathematica

It is proved that if a metrizable locally convex space is not nuclear, then it does not satisfy the Lévy-Steinitz theorem on rearrangement of series.

Regular methods of summability in some locally convex spaces

Costas Poulios (2009)

Commentationes Mathematicae Universitatis Carolinae

Suppose that X is a Fréchet space, a i j is a regular method of summability and ( x i ) is a bounded sequence in X . We prove that there exists a subsequence ( y i ) of ( x i ) such that: either (a) all the subsequences of ( y i ) are summable to a common limit with respect to a i j ; or (b) no subsequence of ( y i ) is summable with respect to a i j . This result generalizes the Erdös-Magidor theorem which refers to summability of bounded sequences in Banach spaces. We also show that two analogous results for some ω 1 -locally convex spaces...

Representing and absolutely representing systems

V. Kadets, Yu. Korobeĭnik (1992)

Studia Mathematica

We introduce various classes of representing systems in linear topological spaces and investigate their connections in spaces with different topological properties. Let us cite a typical result of the paper. If H is a weakly separated sequentially separable linear topological space then there is a representing system in H which is not absolutely representing.

Sequences of 0's and 1's

Grahame Bennett, Johann Boos, Toivo Leiger (2002)

Studia Mathematica

We investigate the extent to which sequence spaces are determined by the sequences of 0's and 1's that they contain.

Sequences of 0's and 1's: sequence spaces with the separable Hahn property

Maria Zeltser (2007)

Studia Mathematica

In [3] it was discovered that one of the main results in [1] (Theorem 5.2), applied to three spaces, contains a nontrivial gap in the argument, but neither the gap was closed nor a counterexample was provided. In [4] the authors verified that all three above mentioned applications of the theorem are true and stated a problem concerning the topological structure of one of these three spaces. In this paper we answer the problem and give a counterexample to the theorem in doubt. Also we establish a...

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