Copyright © 2010 Daniele Ettore Otera and Francesco G. Russo. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Let 𝔛 be a class of groups. A group which does not belong to
𝔛 but all of whose proper quotient groups belong to 𝔛 is called just-non-𝔛 group. The present note is a survey of recent results on the topic with a special attention to topological groups.