s_akbari@rose.ipm.ac.ir, mahdavi@rose.ipm.ac.ir, gmahmudi@rose.ipm.ac.ir

Submission: 1999, July 13

Let $ D $ be a division ring of degree $ m $ over its centre $ F $. Herstein has shown that any finite normal subgroup of $ D^* := GL_1(D) $ is central. Here, as a generalization of this result, it is shown that any finitely generated normal subgroup of $ D^* $ is central. This also solves a problem raised in [1] for finite dimensional division rings. The structure of maximal multiplicative subgroups of an arbitrary division ring $ D $ is then investigated. Given a maximal subgroup $ M $ of $ D^* $ whose centre is algebraic over $ F $, it is proved that if $ M $ satisfies a multilinear polynomial identity over $ F $, then $ [D : F] < \infty $.

1991 Mathematics Subject Classification: 15A33, 16K

Keywords and Phrases: Division rings, maximal subgroups, absolutely irreducible.

Full text: dvi.gz 21 k, dvi 49 k, ps.gz 75 k, pdf.gz 83 k.

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