arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1308.2802math.CTmath.GR
收藏

一类幺半群与自相似群作用II的对应

A correspondence between a class of monoids and self-similar group actions II

Mark V. Lawson, Alistair R. Wallis

摘要:

第一作者表明,在以前的文件中,有一个自相似的群作用和一类左cancellative幺半群称为左里斯幺半群之间的对应关系。这些幺半群可以直接从作用中使用Zappa-Szép乘积构造,这种构造最终可以追溯到Perrot,或者从覆盖双模中作为左可消张量幺半群,利用Nekrashevych的构造,在本文中,我们将张量幺半群构造推广到任意双模。我们把这样产生的幺半群称为列维幺半群,并证明它们正是具有长度函数的可整除幺半群。左Rees幺半群就是左可消Levi幺半群。我们挑出一类不可约的列维幺半群,并证明它们是由其单位群的两个因子之间的同构决定的。不可约的里斯幺半群由此被证明是由它们的单位群的部分自同构决定的;这个结果被证明是有意义的,因为它将不可约的里斯幺半群直接与HNN扩张联系起来。事实上,不可约里斯幺半群的泛群是单位群的一个稳定字母的HNN扩张,并且每个这样的HNN扩张都以这种方式产生。

英文摘要:

The first author showed in a previous paper that there is a correspondence between self-similar group actions and a class of left cancellative monoids called left Rees monoids. These monoids can be constructed either directly from the action using Zappa-Szép products, a construction that ultimately goes back to Perrot, or as left cancellative tensor monoids from the covering bimodule, utilizing a construction due to Nekrashevych, In this paper, we generalize the tensor monoid construction to arbitrary bimodules. We call the monoids that arise in this way Levi monoids and show that they are precisely the equidivisible monoids equipped with length functions. Left Rees monoids are then just the left cancellative Levi monoids. We single out the class of irreducible Levi monoids and prove that they are determined by an isomorphism between two divisors of its group of units. The irreducible Rees monoids are thereby shown to be determined by a partial automorphism of their group of units; this result turns out to be signficant since it connects irreducible Rees monoids directly with HNN extensions. In fact, the universal group of an irreducible Rees monoid is an HNN extension of the group of units by a single stable letter and every such HNN extension arises in this way.

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。

↑