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arXiv 1309.7800math.GR
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关于R^n与R^m的中心半直积的半群猜想

Semigroup Conjectures for Central Semidirect Product of R^n with R^m

Kevin Lui, Viorel Nitica, Siddharth Venkatesh

摘要:

本文证明了关于可解群族H_{mn}中的闭半群的两个新结果,这些闭半群是R^m和R^n的半直积,且其结构同态非平凡地映射到Aut(R^n)的中心.第一个结果指出,由H_{mn}中的集合生成的半群的闭包不包含在具有非空内部的极大半群中,它实际上是一个群。第二个结果表明,在不包含在极大真半群中的H_{mn}的子集中,生成H_{mn}为闭半群的子集是稠密的.这种性质的结果以前只针对幂零群的扩张得到过。这种性质的结果以前只得到交换和幂零李群及其紧扩张。作为本文所发展的技巧的一个应用,我们找到了生成元作为闭群和作为H_{mn}的闭半群的最小个数。

英文摘要:

In this paper we prove two new results about closed semigroups in the family of solvable groups H_{mn} that are semidirect products of R^m and R^n, and for which the structure homomorphism maps nontrivially into the center of Aut(R^n). The first result states that the closure of a semigroup generated by a set in H_{mn} that is not included in a maximal semigroup with nonempty interior is actually a group. The second result states that among the subsets of H_{mn} that are not included in a maximal proper semigroup, those that generate H_{mn} as a closed semigroup are dense. Results of this nature were obtained before only for extensions of nilpotent groups. Results of this nature were obtained before only for abelian and nilpotent Lie groups and their compact extensions. As an application of the technique developed in the paper, we find the minimal number of generators as a closed group and as a closed semigroup of H_{mn}.

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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