On special subgroups of fundamental group
Abstract
Suppose is a nonzero cardinal number, is an ideal on arc connected topological space , and is the subgroup of (the first fundamental group of ) generated by homotopy classes of loops. The main aim of this text is to study s and compare them. Most interest is in and , where denotes the collection of all finite subsets of . We denote with . We prove the following statements: for arc connected topological spaces and if is isomorphic to for all infinite cardinal number , then is isomorphic to ; there are arc connected topological spaces and such that is isomorphic to but is not isomorphic to ; for arc connected topological space we have ; for Hawaiian earring , the sets , , and are pairwise distinct. So s and s will help us to classify the class of all arc connected topological spaces with isomorphic fundamental groups.
Keywords
Cite
@article{arxiv.1704.02802,
title = {On special subgroups of fundamental group},
author = {Fatemah Ayatollah Zadeh Shirazi and Fatemeh Ebrahimifar and Mohammad Ali Mahmoodi},
journal= {arXiv preprint arXiv:1704.02802},
year = {2024}
}
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29 pages