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On the Grossman representations of the automorphism groups of free groups

  • Takao Satoh EMAIL logo
Published/Copyright: May 22, 2025

Abstract

The goal of this paper is to show that, for any k 2 , the subgroup of the automorphism group of a free group consisting of all automorphisms that act trivially on the ( k + 1 ) -th derived quotient of the free group is not finitely generated in some stable range. In order to show this, we consider a slight generalization of results of Grossman in [Representations of the automorphism groups of free groups, J. Algebra 30 (1974), 388–399], and a sequence of descending filtrations of the IA-automorphism group of a free group.

Award Identifier / Grant number: 19K03477 22K03299

Funding statement: This work is supported by JSPS KAKENHI Grant Numbers 19K03477 and 22K03299.

Acknowledgements

The author would like to thank the referee for their careful reading and helpful comments on the original version of the paper. Part of the paper was done in [14] when the author was a master’s student at the University of Tokyo in 2003, over twenty years ago. The author would like to express his sincere gratitude to Professor Nariya Kawazumi, the advisor of the author in those days, for his valuable suggestions.

  1. Communicated by: Dessislava Kochloukova

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Received: 2024-07-30
Revised: 2025-03-28
Published Online: 2025-05-22
Published in Print: 2025-11-01

© 2025 Walter de Gruyter GmbH, Berlin/Boston

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