In [3] Felder and Veselov considered the standard and twisted actions of a finite Coxeter group W on the cohomology H(MW ) of the complement of the complexified hyperplane arrangement MW of W . The twisted action is obtained by combining the standard action with complex conjugation; we refer the reader to [3] for precise statements. In a case by case argument, Felder and Veselov obtain a formul...

Let k be a locally compact non-discrete field with non-Archimedean valuation (Say, just the p-adic numbers Qp), O its ring of integers (say Zp) and P a generator for the maximal ideal of O (i.e. p). In future lectures we will see how Hecke algebras relate to the representation theory of reductive algebraic groups over these fields. The main example to keep in mind is G = GL(n, k). When I talk a...

where the product is over all reflection hyperplanes of G. Let A : V/G -+ @ be the map induced by 6, thus A is the discriminant of G. A subgroup of G is called parabolic if it is generated by all reflections of G fixing elementwise a given subspace of V. The degrees of G are denoted by dl , d2, . . . , d,,. We call a degree of G primitive if it is bigger than the degrees of all proper parabolic...

Let W be an arbitrary Coxeter group, possibly of infinite rank. We describe a decomposition of the centralizer ZW (WI) of an arbitrary parabolic subgroup WI into the center of WI , a Coxeter group and a subgroup defined by a 2-cell complex. Only information about finite parabolic subgroups is required in an explicit computation. Moreover, by using our description of ZW (WI), we reveal a further...

We prove the properties of induced conjugacy classes, without using the original proof by Lusztig and Spaltenstein in the unipotent case, by adapting Borho’s simpler arguments for induced adjoint orbits. We study properties of equivariant fibrations of prehomogeneous affine spaces, especially the existence of relative invariants. We also detect prehomogeneous affine spaces as subquotients of ca...

In this paper, we study the solvmanifolds constructed from any parabolic subalgebras of any semisimple Lie algebras. These solvmanifolds are naturally homogeneous submanifolds of symmetric spaces of noncompact type. We show that the Ricci curvatures of our solvmanifolds coincide with the restrictions of the Ricci curvatures of the ambient symmetric spaces. Consequently, all of our solvmanifolds...

In this article, we consider infinite, non-affine Coxeter groups. These are known to be of exponential growth. We consider the subsets of minimal length coset representatives of parabolic subgroups and show that these sets also have exponential growth. This is achieved by constructing a reflection subgroup of our Coxeter group which is isomorphic to the universal Coxeter group on three generato...

We examine the structure of the Levi component MA in a minimal parabolic subgroup P = MAN of a real reductive Lie group G and work out the cases where M is metabelian, equivalently where p is solvable. When G is a linear group we verify that p is solvable if and only if M is commutative. In the general case M is abelian modulo the center ZG , we indicate the exact structure of M and P , and we ...

In this paper, we develop a theory of Galois descent for equivariant line bundles on partial flag schemes. particular, study computational aspects the classification data attached to characters parabolic subgroups. As an application, classify schemes standard Z[1/2]-forms classical Lie groups.

Let W be a Coxeter group acting as a matrix group by way of the dual of the geometric representation. Let L be the lattice of intersections of all reflecting hyperplanes associated with the reflections in this representation. We show that L is isomorphic to the lattice consisting of all parabolic subgroups of W . We use this correspondence to find all W for which L is supersolvable. In particul...