一个导子李代数的二阶上同调群

Gelfand和Fuks曾计算过圆上向量场李代数的上同调。作者计算了微分算子代数上的2-上循环。本文的目的是计算多元Laurent多项式环上的导子李代数上的二阶上同调群,把[1]的讨论推广到多元的情形。 设C[t_1,t_2,t_1~(-1),t_2~(-1)]是复数域C上的二元Laurent多项式环[t_1,t_2,t_1~(-1),t_2~(-1)]是C[t_1,t_2,t_1~(-1),t_2~(-1)]上的导子作成的李代数,其中,·有基{t_1~ml+~1t_2~m2D_1,t_1~mlt_心~m2~(+1) D_2|m_1,m_2∈Z)。     

Classification of Cartan Matrices of Hyperbolic Type

In the theory of finite dimensional semisimple Lie algebras,it is known thatthe Cartan matrix A=(a_(ij))_i~n, i=1 has the following properties: (1)a_(ii)=2,i=1,…,n; (2)a_(ij)≤0 for i≠j,a_(ij)∈Z; (3)a_(ij)=0 a_(ji)=0. Now if a matrix A=(a_(ij))_i~n,j\j=1 satisfies (1),(2),(3),then A is called