Affiliation: | Department of Mathematics, Hebrew University, Jerusalem 91904, Israel P. H. Kropholler ; School of Mathematical Sciences, Queen Mary & Westfield College, Mile End Road, London E1 4NS, United Kingdom A. Lubotzky ; Department of Mathematics, Hebrew University, Jerusalem 91904, Israel A. Shalev ; Department of Mathematics, Hebrew University, Jerusalem 91904, Israel |
Abstract: | In this paper we study the set of -powers in certain finitely generated groups . We show that, if is soluble or linear, and contains a finite index subgroup, then is nilpotent-by-finite. We also show that, if is linear and has finite index (i.e. may be covered by finitely many translations of ), then is soluble-by-finite. The proof applies invariant measures on amenable groups, number-theoretic results concerning the -unit equation, the theory of algebraic groups and strong approximation results for linear groups in arbitrary characteristic. |