Neighborhoods of the identity of the free abelian topological groups
Non-abelian group structure on the Urysohn universal space
We prove that there exists a non-abelian group structure on the Urysohn universal metric space. More precisely, we introduce a variant of the Graev metric that enables us to construct a free group with countably many generators equipped with a two-sided invariant metric that is isometric to the rational Urysohn space. We list several related open problems.
Normed versus topological groups: Dichotomy and duality [Book]
Note on a generalization of a theorem of Bogolioùboff