Expansivity and Roquette Groups
  One looks at expansive subgroups in particular examples of Roquette groups. This study is motivated by the importance of expansive subgroups in the theory of stabilizing bisets highlighted in [BouThe]. In this paper we prove the non-existence of expansive subgroups with trivial G-core in different examples of Roquette groups G. 
Alex Monnard
math.GR