Optimal Subgroups and Applications to Nilpotent Elements
نویسنده
چکیده
Let G be a reductive group acting on an affine variety X , and let x ∈ X be a point whose G-orbit is not closed. In this paper, we study G.R. Kempf’s optimal class of cocharacters of G attached to the point x; in particular, we consider how this optimality transfers to subgroups of G. Our main result says that if K is a G-completely reducible subgroup of G which fixes x, then the optimal class for CG(K) 0 is just the set of optimal cocharacters of G which evaluate in CG(K) . We then apply our results in the case that G acts on its Lie algebra via the adjoint representation to obtain some new information about cocharacters associated to nilpotent elements in good characteristic.
منابع مشابه
Results on Engel Fuzzy Subgroups
In the classical group theory there is an open question: Is every torsion free n-Engel group (for n ≥ 4), nilpotent?. To answer the question, Traustason [11] showed that with some additional conditions all 4-Engel groups are locally nilpotent. Here, we gave some partial answer to this question on Engel fuzzy subgroups. We show that if μ is a normal 4-Engel fuzzy subgroup of ...
متن کاملNilpotent groups with three conjugacy classes of non-normal subgroups
Let $G$ be a finite group and $nu(G)$ denote the number of conjugacy classes of non-normal subgroups of $G$. In this paper, all nilpotent groups $G$ with $nu(G)=3$ are classified.
متن کاملThe influence of S-embedded subgroups on the structure of finite groups
Let H be a subgroup of a group G. H is said to be S-embedded in G if G has a normal T such that HT is an S-permutable subgroup of G and H ∩ T ≤ H sG, where H denotes the subgroup generated by all those subgroups of H which are S-permutable in G. In this paper, we investigate the influence of minimal S-embedded subgroups on the structure of finite groups. We determine the structure the finite grou...
متن کاملNILPOTENT GRAPHS OF MATRIX ALGEBRAS
Let $R$ be a ring with unity. The undirected nilpotent graph of $R$, denoted by $Gamma_N(R)$, is a graph with vertex set ~$Z_N(R)^* = {0neq x in R | xy in N(R) for some y in R^*}$, and two distinct vertices $x$ and $y$ are adjacent if and only if $xy in N(R)$, or equivalently, $yx in N(R)$, where $N(R)$ denoted the nilpotent elements of $R$. Recently, it has been proved that if $R$ is a left A...
متن کاملNilpotent Elements in Skew Polynomial Rings
Letbe a ring with an endomorphism and an -derivationAntoine studied the structure of the set of nilpotent elements in Armendariz rings and introduced nil-Armendariz rings. In this paper we introduce and investigate the notion of nil--compatible rings. The class of nil--compatible rings are extended through various ring extensions and many classes of nil--compatible rings are constructed. We al...
متن کامل