Liliana Lancellotti

New variations on the theme of Baer’s theorem

Abstract Let $$\gamma _s(G)$$ γ s ( G ) and $$Z_s(G)$$ Z s ( G ) denote the s -th terms of the lower and upper central series of a group G , respectively. A classical theorem by R. Baer states that if $$Z_s(G)$$ Z s ( G ) has finite index in G , then $$\gamma _{s+1}(G)$$ γ s + 1...