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Uniformly perfect finitely generated simple left orderable groups

Published online by Cambridge University Press:  08 October 2019

JAMES HYDE
Affiliation:
Mathematical Institute, University of St. Andrews, UK email jameshydemaths@gmail.com
YASH LODHA
Affiliation:
Institute of Mathematics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland email yash.lodha@epfl.ch
ANDRÉS NAVAS
Affiliation:
Departamento de Matemáticas y Ciencia de la Computación, Universidad de Santiago de Chile, Santiago, Chile Unidad Cuernavaca Instituto de Matemáticas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico email andres.navas@usach.cl
CRISTÓBAL RIVAS
Affiliation:
Departamento de Matemáticas y Ciencia de la Computación, Universidad de Santiago de Chile, Mexico email cristobal.rivas@usach.cl
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Abstract

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We show that the finitely generated simple left orderable groups $G_{\!\unicode[STIX]{x1D70C}}$ constructed by the first two authors in Hyde and Lodha [Finitely generated infinite simple groups of homeomorphisms of the real line. Invent. Math. (2019), doi:10.1007/s00222-019-00880-7] are uniformly perfect—each element in the group can be expressed as a product of three commutators of elements in the group. This implies that the group does not admit any homogeneous quasimorphism. Moreover, any non-trivial action of the group on the circle, which lifts to an action on the real line, admits a global fixed point. It follows that any faithful action on the real line without a global fixed point is globally contracting. This answers Question 4 of the third author [A. Navas. Group actions on 1-manifolds: a list of very concrete open questions. Proceedings of the International Congress of Mathematicians, Vol. 2. Eds. B. Sirakov, P. Ney de Souza and M. Viana. World Scientific, Singapore, 2018, pp, 2029–2056], which asks whether such a group exists. This question has also been answered simultaneously and independently, using completely different methods, by Matte Bon and Triestino [Groups of piecewise linear homeomorphisms of flows. Preprint, 2018, arXiv:1811.12256]. To prove our results, we provide a characterization of elements of the group $G_{\!\unicode[STIX]{x1D70C}}$ which is a useful new tool in the study of these examples.

Information

Type
Original Article
Copyright
© Cambridge University Press, 2019