Sh:751
- Eda, K., & Shelah, S. (2002). The non-commutative Specker phenomenon in the uncountable case. J. Algebra, 252(1), 22–26. arXiv: math/0011231 DOI: 10.1016/S0021-8693(02)00045-5 MR: 1922382
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Abstract:
An infinitary version of the notion of free products has been introduced and investigated by G.Higman. Let G_i (for i\in I) be groups and \ast_{i\in X} G_i the free product of G_i (i\in X) for X \Subset I and p _{XY}:\ast_{i\in Y} G_{i}\rightarrow \ast_{i\in X} G_{i} the canonical homomorphism for X\subseteq Y \Subset I. ( X\Subset I denotes that X is a finite subset of I.) Then, the unrestricted free product is the inverse limit \lim (\ast_{i\in X} G_i, p_{XY}: X\subseteq Y\Subset I).We remark \ast_{i\in\emptyset} G_i=\{e\}. We prove:
Theorem: Let F be a free group. Then, for each homomorphism h: \lim \ast G_i \to F there exist countably complete ultrafilters u_0,\cdots,u_m on I such that h = h\cdot p_{U_0\cup \cdots\cup U_m} for every U_0\in u_0,\cdots ,U_m\in u_m.
If the cardinality of the index set I is less than the least measurable cardinal, then there exists a finite subset X_0 of I and a homomorphism \overline{h}:\ast _{i\in X_0}G_i\to F such that h=\overline{h}\cdot p_{X_0}, where p_{X_0}:\lim\ast G_i\to \ast_{i\in X_0}G_i is the canonical projection.
- Version 2000-10-12_11 (4p) published version (5p)
Bib entry
@article{Sh:751,
author = {Eda, Katsuya and Shelah, Saharon},
title = {{The non-commutative Specker phenomenon in the uncountable case}},
journal = {J. Algebra},
fjournal = {Journal of Algebra},
volume = {252},
number = {1},
year = {2002},
pages = {22--26},
issn = {0021-8693},
mrnumber = {1922382},
mrclass = {20E06 (20K25)},
doi = {10.1016/S0021-8693(02)00045-5},
note = {\href{https://arxiv.org/abs/math/0011231}{arXiv: math/0011231}},
arxiv_number = {math/0011231}
}