%0 Journal Article %T Arnautov's problems on semitopological isomorphisms %A Dikran Dikranjan %A Anna Giordano Bruno %J Mathematics %D 2011 %I arXiv %X Semitopological isomorphisms of topological groups were introduced by Arnautov, who posed several questions related to compositions of semitopological isomorphisms and the groups G (we call them Arnautov groups) such that for every group topology T on G every semitopological isomorphism with domain (G,T) is necessarily open (i.e., a topological isomorphism). We propose a different approach to these problems by introducing appropriate new notions, necessary for a deeper understanding of Arnautov groups. This allows us to find some partial answers and many examples. In particular, we discuss the relation with minimal groups and non-topologizable groups. %U http://arxiv.org/abs/1105.3649v1