English

Algebraic and topological properties of some sets in $l_1$

General Topology 2013-05-28 v1 Functional Analysis

Abstract

For a sequence xl1c00x \in l_1 \setminus c_{00}, one can consider the set E(x)E(x) of all subsums of series n=1x(n)\sum_{n=1}^{\infty} x(n). Guthrie and Nymann proved that E(x)E(x) is one of the following types of sets: (I) a finite union of closed intervals; (C) homeomorphic to the Cantor set; (MC) homeomorphic to the set TT of subsums of n=1b(n)\sum_{n=1}^\infty b(n) where b(2n1)=3/4nb(2n-1) = 3/4^n and b(2n)=2/4nb(2n) = 2/4^n. By II, CC and MCMC we denote the sets of all sequences xl1c00x \in l_1 \setminus c_{00}, such that E(x)E(x) has the corresponding property. In this note we show that II and CC are strongly c\mathfrak{c}-algebrable and MCMC is c\mathfrak{c}-lineable. We show that CC is a dense GδG_\delta-set in l1l_1 and II is a true FσF_\sigma-set. Finally we show that II is spaceable while CC is not spaceable.

Keywords

Cite

@article{arxiv.1208.3058,
  title  = {Algebraic and topological properties of some sets in $l_1$},
  author = {T. Banakh and A. Bartoszewicz and Sz. Glab and E. Szymonik},
  journal= {arXiv preprint arXiv:1208.3058},
  year   = {2013}
}

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15 pages