Startseite Critical maximal subgroups and conjugacy of supplements in finite soluble groups
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Critical maximal subgroups and conjugacy of supplements in finite soluble groups

  • Barbara Baumeister EMAIL logo und Gil Kaplan
Veröffentlicht/Copyright: 18. Oktober 2017

Abstract

Let G be a finite group with an abelian normal subgroup N. When does N have a unique conjugacy class of complements in G? We consider this question with a focus on properties of maximal subgroups. As corollaries we obtain Theorems 1.6 and 1.7 which are closely related to a result by Parker and Rowley on supplements of a nilpotent normal subgroup [3, Theorem 1]. Furthermore, we consider families of maximal subgroups of G closed under conjugation whose intersection equals Φ(G). In particular, we characterize the soluble groups having a unique minimal family with this property (Theorem 2.3, Remark 2.4). In the case when Φ(G)=1, these are exactly the soluble groups in which each abelian normal subgroup has a unique conjugacy class of complements.


Dedicated to the memory of Wolfgang Gaschütz (11.6.1920–7.11.2016)



Communicated by Christopher Parker


Acknowledgements

The authors are indebted to Professor Hermann Heineken for fruitful discussions which helped to improve this paper. We also thank Chris Parker for his comments, and the second author wishes to thank Project C13 within SFB 701 at the University of Bielefeld for its hospitality.

References

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Received: 2017-4-12
Revised: 2017-9-8
Published Online: 2017-10-18
Published in Print: 2018-1-1

© 2017 Walter de Gruyter GmbH, Berlin/Boston

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