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On Universal Schauder Bases in Non-Archimedean Fréchet Spaces

Published online by Cambridge University Press:  20 November 2018

Wiesław Śliwa*
Affiliation:
Faculty of Mathematics and Computer Science A. Mickiewicz University ul. Umultowska 87 61-614 Poznán Poland, e-mail: sliwa@amu.edu.pl
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Abstract

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It is known that any non-archimedean Fréchet space of countable type is isomorphic to a subspace of $c_{0}^{\mathbb{N}}$. In this paper we prove that there exists a non-archimedean Fréchet space $U$ with a basis $({{u}_{n}})$ such that any basis $({{x}_{n}})$ in a non-archimedean Fréchet space $X$ is equivalent to a subbasis $({{u}_{kn}})$ of $({{u}_{n}})$. Then any non-archimedean Fréchet space with a basis is isomorphic to a complemented subspace of $U$. In contrast to this, we show that a non-archimedean Fréchet space $X$ with a basis $({{x}_{n}})$ is isomorphic to a complemented subspace of $c_{0}^{\mathbb{N}}$ if and only if $X$ is isomorphic to one of the following spaces: ${{c}_{0}},\,{{c}_{0}}\,\times \,{{\mathbb{K}}^{\mathbb{N}}},\,{{\mathbb{K}}^{\mathbb{N}}},\,c_{0}^{\mathbb{N}}$. Finally, we prove that there is no nuclear non-archimedean Fréchet space $H$ with a basis $({{h}_{n}})$ such that any basis $({{y}_{n}})$ in a nuclear non-archimedean Fréchet space $Y$ is equivalent to a subbasis $({{h}_{kn}})$ of $({{h}_{n}})$.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2004

References

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