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arXiv 2106.02541math.GR
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几乎标准树上的自由循环群、自同构和作用

Free-by-cyclic groups, automorphisms and actions on nearly canonical trees

Naomi Andrew, Armando Martino

摘要:

本文研究了自由循环群的自同构群,证明了在下列情况下,自同构群是可生成的:(i)当定义自同构具有线性增长时;(ii)当基础自由群的秩至多为3时。我们使用的技术是行动的树木,包括树木的圆柱由于Guirardel和莱维特,相对双曲的自由的循环群(由于Gaueland和Lustig,Ghosh,和Dahmani和李)和过滤的自同构群保持一棵树,以下巴斯和江,莱维特。我们的一般策略是产生一个不变树的组和研究,通常减少初始问题的某种麦库尔问题(研究自同构群固定一些集合共轭类的子群)的一组较低的复杂性。进一步推进这些技术的障碍,归纳,是在寻找一个合适的不变树,并在显示相关的McCool组是可重复生成的。

英文摘要:

We study the automorphism groups of free-by-cyclic groups and show these are finitely generated in the following cases: (i) when defining automorphism has linear growth and (ii) when the rank of the underlying free group has rank at most 3. The techniques we use are actions on trees, including the trees of cylinders due to Guirardel and Levitt, the relative hyperbolicity of free-by-cyclic groups (due to Gautero and Lustig, Ghosh, and Dahmani and Li) and the filtration of the automorphisms of a group preserving a tree, following Bass and Jiang, and Levitt. Our general strategy is to produce an invariant tree for the group and study that, usually reducing the initial problem to some sort of McCool problem (the study of an automorphism group fixing some collection of conjugacy classes of subgroups) for a group of lower complexity. The obstruction to pushing these techniques further, inductively, is in finding a suitable invariant tree and in showing that the relevant McCool groups are finitely generated.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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