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SL(3,p~n)的Cartan不变量
The Cartan Invariants of SL(3,p~n)
【摘要】 <正>K表示特征数p>0的代数闭域。G是K上单连通半单代数群。Γn=G(FPn)是Pn个元素的有限域上型G的有限Chevalley群,它在K上的群代数是KΓn.Λn表示不同构的不可约KΓn-模Mλ,n的指标集,也是不同构的主不可分解KΓn-模Rλ,n的指标集,它可以看作G的权格X中“限制”优势权的集合Xpn。因此|Λn|=p(R·rankG.Γn的Cartan不变量C(λ,μ(λ,μ∈Λn)等于Mμ,n作为Rλ,n的合成因子出现的重数,形成|Λn|阶对称矩阵。
【Abstract】 Let G = SL(3,K) be a simply connected, semi-simple algebraic group of type A2 over an algebraically closed i’ield K of characteristic p>0. Let Γn = SL(3,pn) be a finite subgroup consisting of fixed points oi’ the Frobenius morphism Fn of G.In this paper, a method for computing the Cartan invariants of Γn for p>3 is. given and the Cartan matrix of SL(3,7) is computed. We mainly deal with Γ1 and find the KΓ1- compos it ion factors of each principal indecomposable KΓ1-module- by the following way: It is known that the principal indecomposable μ1-module Qλ.1 has a G-module structure, we first prove that it has a G-module filtration with quotients isomorphic to Weyl modules and give a general description of its quotients (§ 1.4. Theorems). Next we write general expressions of decomposition of Qλ.1 into G-composition factors and μ1-composition factors (§4.5. Theorem 10 and Theorem 11). Using deformation we obtain all KΓ1-composition factors of Qλ1(§1.6.). Since the restriction of Qλ.1 to KΓ1is still projective, it can be written as a direct sum principal indecomposable KΓ1-modules, we thus obtain all KΓ1-composition factors of Rλ.1 We further show how to generalize our method to compute the KΓn-composition factors of Rλn for all and describe the behaviours of KΓn-compositi6n factors of Rλ.n when λ is in a general position in An (§3.).
- 【文献出处】 数学研究与评论 ,Journal of Mathematical Research and Exposition , 编辑部邮箱 ,1982年04期
- 【被引频次】10
- 【下载频次】15