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Amenable actions of amalgamated free products

2008/10/14 by Soyoung Moon, Moon, Soyoung
Mathematics · #20E06 #43A07 #57M07 #Advanced Operator Algebra Research #FOS: Mathematics #Geometric and Algebraic Topology #Group Theory (math.GR) #Homotopy and Cohomology in Algebraic Topology #math.GR #msc:20E06 #msc:43A07 #msc:57M07

paper · pdf · doi:10.48550/arxiv.0810.2456

Minor corrections. To appear in Groups, Geometry and Dynamics.

openalex publication_date 2008/10/14 · arxiv created 2010/03/21 · arxiv updated 2010/03/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We prove that the amalgamated free product of two free groups of rank two over a common cyclic subgroup, admits an amenable, faithful, transitive action on an infinite countable set. We also show that any finite index subgroup admits such an action, which applies for example to surface groups and fundamental groups of surface bundles over \mathbbS1.

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