Publication
Ulam asked whether every connected Lie group can be represented on a countable structure. This is known in the linear case. We establish it for the first family of non-linear groups, namely in the nilpotent case. Further context is discussed to illustrate the relevance of nilpotent groups for Ulam's problem.
Donna Testerman, Martin W. Liebeck
Jeremy Luterbacher, Songlan Sun, Stefania Bertella, Anastasiia Komarova