Some new facts about group 𝒢 generated by the family of convergent permutations

• Main Authors: Wituła Roman, Hetmaniok Edyta, Słota Damian
• Format: Article
• Language: English
• Published: De Gruyter 2017-05-01
• Series: Open Mathematics
• Subjects: convergent permutations; divergent permutations; b-connected permutations; 40a05; 05a99
• Online Access: http://www.degruyter.com/view/j/math.2017.15.issue-1/math-2017-0048/math-2017-0048.xml?format=INT

The aim of this paper is to present some new and essential facts about group 𝒢 generated by the family of convergent permutations, i.e. the permutations on ℕ preserving the convergence of series of real terms. We prove that there exist permutations preserving the sum of series which do not belong to 𝒢. Additionally, we show that there exists a family G (possessing the cardinality equal to continuum) of groups of permutations on ℕ such that each one of these groups is different than 𝒢 and is composed only from the permutations preserving the sum of series. This result substantially strengthens some old Pleasants’ result.