Hostname: page-component-78c5997874-v9fdk Total loading time: 0 Render date: 2024-11-10T15:54:38.356Z Has data issue: false hasContentIssue false

Strange permutation representations of free groups

Published online by Cambridge University Press:  09 April 2009

Meenaxi Bhattacharjee
Affiliation:
Department of Mathematics Indian Institute of Technology GuwahatiGuwahati Assam 781039India e-mail: meenaxi@iitg.ernet.in
Dugald MacPherson
Affiliation:
Department of Pure Mathematics University of LeedsLeeds LS2 9JTEngland e-mail: h.d.macPherson@leeds.ac.uk
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Certain permutation representations of free groups are constructed by finite approximation. The first is a construction of a cofinitary group with special properties, answering a question of Tim Wall published by Cameron. The second yields, via a method of Kepert and Willis, a totally disconnected locally compact group which is compactly generated and uniscalar but has no compact open normal subgroup. Finally, an oligomorphic group of automorphisms of the random graph is built, all of whose non-trivial subgroups have just finitely many orbits.

MSC classification

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 2003

References

[1]Cameron, P. J., Oligomorphic permutation groups, London Math. Soc. Lecture Notes 152 (Cambridge University Press, Cambridge, 1990).CrossRefGoogle Scholar
[2]Cameron, P. J., ‘Cofinitary permutation groups’, Bull. London Math. Soc. 28 (1996), 113140.CrossRefGoogle Scholar
[3]Dixon, J. D., ‘Most finitely generated permutation groups are free’, Bull. London Math. Soc. 22 (1990), 222226.CrossRefGoogle Scholar
[4]Higman, D. G., ‘Intersection matrices for finite permutation groups’, J. Algebra 6 (1967), 2242.CrossRefGoogle Scholar
[5]Karolyi, G., Kovacs, S. J. and Palfy, P. P., ‘Doubly transitive permutation groups with abelian stabilisers’, Aequationes Math. 39 (1990), 161166.CrossRefGoogle Scholar
[6]Kepert, A. and Willis, G. A., ‘Scale functions and tree ends’, J. Austral. Math. Soc. 70 (2001), 273292.CrossRefGoogle Scholar
[7]MacPherson, H. D., ‘Permutation groups whose subgroups have just finitely many orbits’, in: Ordered groups and infinite permutation groups (ed. Holland, W. C.) (Kluwer, 1996) pp. 221231.CrossRefGoogle Scholar
[8]Mazurov, V. D., ‘On doubly transitive permutation groups’, Sibirsk. Mat. Zh. 31 (1990), 102104.Google Scholar
[9]Willis, G. A., ‘The structure of totally disconnected locally compact groups’, Math. Ann. 300 (1994), 341363.CrossRefGoogle Scholar
[10]Willis, G. A., ‘Totally disconnected nilpotent locally compact groups’, Bull. Austral. Math. Soc. 55 (1997), 143146.CrossRefGoogle Scholar