Asadollah Faramarzi Salles

Department of Mathematics, Damghan University, Damghan, Iran.

[ 1 ] - Some Results on Baer's Theorem

Baer has shown that, for a group G, finiteness of G=Zi(G) implies finiteness of ɣi+1(G). In this paper we will show that the converse is true provided that G=Zi(G) is finitely generated. In particular, when G is a finite nilpotent group we show that |G=Zi(G)| divides |ɣi+1(G)|d′ i(G), where d′i(G) =(d( G /Zi(G)))i.

[ 2 ] - A relation between infinite subsets and exterior center in groups

Let G be a group. Neumann to answer a question of Paul Erdos proved that every infinite subset of G has two different comuting elements if and only if G is center-by-finite. In this paper, we deal with Erdoschr('39')s question in different aspect and we show that every infinite subset X of G has two different elements x and y such that x^y=1 if and only if the exterior center of G ihas finit...

Co-Authors