A weak Zassenhaus lemma for discrete subgroups of Diff(I)
arXiv:1211.1086
Abstract
We prove a weaker version of Zassenhaus Lemma (also known as Margulis Lemma) for subgroups of Diff(I). We also show that a group with commutator subgroup containing a free subsemigroup does not admit a C_0-discrete faithful representation in Diff(I).
Several presentational changes made. (by the suggestions of the referees)