It is proven that an infinite-dimensional Banach space (considered as an Abelian topological group) is not topologically isomorphic to a subgroup of a product of $\sigma $-compact (or more generally, $o$-bounded) topological groups. This answers a question of M. Tkachenko.
@article{119212, author = {Taras O. Banakh}, title = {Locally minimal topological groups and their embeddings into products of $o$-bounded groups}, journal = {Commentationes Mathematicae Universitatis Carolinae}, volume = {41}, year = {2000}, pages = {811-815}, zbl = {1049.54034}, mrnumber = {1800163}, language = {en}, url = {http://dml.mathdoc.fr/item/119212} }
Banakh, Taras O. Locally minimal topological groups and their embeddings into products of $o$-bounded groups. Commentationes Mathematicae Universitatis Carolinae, Tome 41 (2000) pp. 811-815. http://gdmltest.u-ga.fr/item/119212/
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