On definable subgroups of the fundamental group

被引:2
|
作者
Corson, Samuel M. [1 ]
机构
[1] Univ Basque Country, Ikerbasque Basque Fdn Sci & Matemat Saila, Sarriena S-N, E-48940 Leioa, Bizkaia, Spain
关键词
Fundamental group; Metric spaces; Descriptive set theory;
D O I
10.1016/j.topol.2019.03.007
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
We present several new theorems concerning the first fundamental group of a path connected metric space. Among the results proven are strengthenings of the main theorems of [23] and [7]. A compactness theorem for the fundamental group of a Peano continuum is given. We also show that a free decomposition of the fundamental group of a locally path connected Polish space cannot be nonconstructive. Numerous other results and examples illustrating the sharpness of our theorems are provided. (C) 2019 Elsevier B.V. All rights reserved.
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页码:336 / 357
页数:22
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