Survey on matched pairs of groups-an elementary approach to the ESS-LYZ theory
Survey on matched pairs of groups-an elementary approach to the ESS-LYZ theory
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配对群体的调查——ESS-LYZ理论的基本方法
DOI:
10.4064/bc61-0-19
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发表时间:
2003
期刊:
影响因子:
--
通讯作者:
M. Takeuchi
中科院分区:
文献类型:
--
作者:
M. Takeuchi
The theory of matched pairs of groups is surveyed with special interest in applications to braided groups and quasitriangular structures on the bi-smash product Hopf algebra. Introduction. In 1981, I introduced the notion of a matched pair of groups (S,B) and defined the bi-smash product Hopf algebra (kS)∗ ⊗ kB over a field k, when S is a finite group [T], motivated by W. M. Singer’s work [Si] on Hopf algebra extensions. Later, S. Majid [Mj] extended and applied this work in the study of quantum groups. Further, the cohomology theory of matched pairs of Hopf algebras was studied by I. Hofstetter [H] and A. Masuoka [Ms1], [Ms2]. During this research, Masuoka found out that the notion of a matched pair of groups had been obtained essentially by G. I. Kac [K] in 1968 and that the cohomology theory of matched pairs of groups had been studied there. Recently, some interesting progress in the study of matched pairs of groups has been made by two groups of algebraists, ESS (Etingof, Schedler, Soloviev) and LYZ (Lu, Yan, Zhu), during their study of set-theoretical solutions of the Yang-Baxter equation. Especially, the group ESS [ESS] has obtained some deep results on classification of finite braided sets. In this survey, I give an elementary and diagrammatic approach to the introductory part of the ESS-LYZ theory. This will enable the reader to appreciate their deeper results (which are not discussed here) more easily. On the other hand, the latter group LYZ has obtained some interesting construction of quasitriangular structures on the bi-smash product Hopf algebra H(S,B) = (kS)∗ ⊗ kB [LYZ2]. I also give a natural categorical explanation of this construction, based on Masuoka’s observation [Ms3]. In §1, we review the notion of a matched pair of groups (S,B) and matched product B ./ S, and explain the matched pair condition by means of diagrams of the form 2000 Mathematics Subject Classification: 16W35, 18D10. The paper is in final form and no version of it will be published elsewhere.