On the Automorphisms of the Fundamental Group of a Graph of Groups and Their Fixed Points

• 来源期刊: 代数集刊（英文版）
• 关键词: automorphisms groups acting on trees fixed subgroups
• 年，卷（期）: 2002,（4）
• 页码范围: 445-454
• 页数: 10页
• 语种: 英文

摘要

Let G be the fundamental group of a graph of groups and X the corresponding universal tree. We consider the extension of the action of G on X to an action of the subgroup of automorphisms of G which map vertex groups onto conjugates of themselves and obtain a structure theorem for this subgroup.We also prove results that can be used to give bounds for the complexity of the graph of groups decomposition of the fixed subgroups of these automorphisms.