|
In algebra, the Nichols algebra of a braided vector space (with the braiding often induced by a finite group) is a braided Hopf algebra which is denoted by and named after the mathematician Warren Nichols. It takes the role of quantum Borel part of a pointed Hopf algebra 〔 such as a quantum groups and their well known finite-dimensional truncations. Nichols algebras can immediately be used to write down new such quantum groups by using the Radford biproduct〔 The classification of all such Nichols algebras and even all associated quantum groups (see Application) is recently progressing rapidly, although still much is open: The case of an abelian group has been solved 2005,〔 but otherwise this phenomenon seems to be a very rare occasion, with a handful examples known and powerful negation criteria established (see below). Also, see here for a list List of finite-dimensional Nichols algebras. The finite-dimensional theory is greatly governed by a theory of root systems and Dynkin diagrams, strikingly similar to those of semisimple Lie algebras.〔 A comprehensive introduction is found in the lecture of Heckenberger 〔 ==Definition== Consider a Yetter–Drinfeld module ''V'' in the Yetter–Drinfeld category is always a Braided Hopf algebra. The coproduct and counit of is defined in such a way that the elements of are primitive, that is for all :: :: The Nichols algebra can be uniquely defined by several equivalent characterizations, some of which focus on the Hopf algebra structure and some are more combinatorial. Regardless, determining the Nichols algebra explicitly (even decide if it's finite-dimensional) can be very difficult and is open in several concrete instances (see below). 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Nichols algebra」の詳細全文を読む スポンサード リンク
|