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arXiv · 1103.0725

The word problem for some uncountable groups given by countable words

Oleg Bogopolski·Andreas Zastrow
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Abstract

We investigate the fundamental group of Griffiths' space, and the first singular homology group of this space and of the Hawaiian Earring by using (countable) reduced tame words. We prove that two such words represent the same element in the corresponding group if and only if they can be carried to the same tame word by a finite number of word transformations from a given list. This enables us to construct elements with special properties in these groups. By applying this method we prove that the two homology groups contain uncountably many different elements that can be represented by infinite concatenations of countably many commutators of loops. As another application we give a short proof that these homology groups contain the direct sum of 2^{\aleph_0} copies of \mathbb{Q}. Finally, we show that the fundamental group of Griffith's space contains \mathbb{Q}.

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BibTeXRIS

Oleg Bogopolski, Andreas Zastrow. 2011-03-03. The word problem for some uncountable groups given by countable words. https://arxiv.org/abs/1103.0725

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