Let O be a nilpotent orbit in the Lie algebra n( ) and let V be an orbital variety contained in O. Let P be the largest parabolic subgroup of SL(n, ) stabilizing V. We describe nilpotent orbits such that all the orbital varieties in them have a dense P orbit and show that for n big enough the majority of nilpotent orbits do not fulfill this. Résumé Soit O une orbite nilpotente dans l’algèbre de...

The definition of index goes back to Dixmier [3, 11.1.6]. This notion is important in Representation Theory and also in Invariant Theory. By Rosenlicht’s theorem [12], generic orbits of an arbitrary action of a linear algebraic group on an irreducible algebraic variety are separated by rational invariants; in particular, ind g = tr.degK(g). The index of a reductive algebra equals its rank. Comp...

After introducing double derivations of $n$-Lie algebra $L$ we‎ ‎describe the relationship between the algebra $mathcal D(L)$ of double derivations and the usual‎ ‎derivation Lie algebra $mathcal Der(L)$‎. ‎In particular‎, ‎we prove that the inner derivation algebra $ad(L)$‎ ‎is an ideal of the double derivation algebra $mathcal D(L)$; we also show that if $L$ is a perfect $n$-Lie algebra‎ ‎wit...

In the joint paper [10], the authors established a connection between representations of a finite Lie algebra g0 over a finite field Fq and their algebraic extension g = g0 ⊗Fq k for k = F̄q , which particularly describes irreducible representations of g0 through irreducible representations of g. In this process, the so-called Fg-stable modules play a crucial role, which arise from the Frobenius...

We organize the nilpotent orbits in the exceptional complex Lie algebras into series and show that within each series the dimension of the orbit is a linear function of the natural parameter a = 1, 2, 4, 8, respectively for f4, e6, e7, e8. We observe similar regularities for the centralizers of nilpotent elements in a series and graded components in the associated grading of the ambient Lie alg...