On the set of limit points of the partial sums of series rearranged by a given divergent permutation |
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Authors: | Roman Witu a |
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Affiliation: | aInstitute of Mathematics, Silesian University of Technology, Kaszubska 23, 44-100 Gliwice, Poland |
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Abstract: | We give a new characterization of divergent permutations. We prove that for any divergent permutation p, any closed interval I of (the 2-point compactification of ) and any real number sI, there exists a series ∑an of real terms convergent to s such that I=σap(n) (where σap(n) denotes the set of limit points of the partial sums of the series ∑ap(n)). We determine permutations p of for which there exists a conditionally convergent series ∑an such that ∑ap(n)=+∞. If the permutation p of possesses the last property then we prove that for any and there exists a series ∑an convergent to α and such that σap(n)=[β,+∞]. We show that for any countable family P of divergent permutations there exist conditionally convergent series ∑an and ∑bn such that any series of the form ∑ap(n) with pP is convergent to the sum of ∑an, while for every pP. |
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Keywords: | Limit points Divergent permutations |
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