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ON GROUPS WITH FINITE CONJUGACY CLASSES IN A VERBAL SUBGROUP

Published online by Cambridge University Press:  08 June 2017

COSTANTINO DELIZIA
Affiliation:
Dipartimento di Matematica, Università di Salerno, Via Giovanni Paolo II, 132 - 84084 - Fisciano (SA), Italy email cdelizia@unisa.it
PAVEL SHUMYATSKY
Affiliation:
Department of Mathematics, University of Brasilia, Brasilia-DF, 70910-900, Brazil email pavel@unb.br
ANTONIO TORTORA*
Affiliation:
Dipartimento di Matematica, Università di Salerno, Via Giovanni Paolo II, 132 - 84084 - Fisciano (SA), Italy email antortora@unisa.it
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Abstract

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Let $w$ be a group-word. For a group $G$, let $G_{w}$ denote the set of all $w$-values in $G$ and let $w(G)$ denote the verbal subgroup of $G$ corresponding to $w$. The group $G$ is an $FC(w)$-group if the set of conjugates $x^{G_{w}}$ is finite for all $x\in G$. It is known that if $w$ is a concise word, then $G$ is an $FC(w)$-group if and only if $w(G)$ is $FC$-embedded in $G$, that is, the conjugacy class $x^{w(G)}$ is finite for all $x\in G$. There are examples showing that this is no longer true if $w$ is not concise. In the present paper, for an arbitrary word $w$, we show that if $G$ is an $FC(w)$-group, then the commutator subgroup $w(G)^{\prime }$ is $FC$-embedded in $G$. We also establish the analogous result for $BFC(w)$-groups, that is, groups in which the sets $x^{G_{w}}$ are boundedly finite.

Type
Research Article
Copyright
© 2017 Australian Mathematical Publishing Association Inc. 

Footnotes

The second author was supported by the ‘National Group for Algebraic and Geometric Structures and their Applications’ (GNSAGA – INdAM) and FAPDF-Brazil.

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