A Criterion for n-Fold Transitivity of Transformation Groups.
A Moebius-Like Formula in the Schubert Calcalus.
Affine braid group actions on derived categories of Springer resolutions
In this paper we construct and study an action of the affine braid group associated with a semi-simple algebraic group on derived categories of coherent sheaves on various varieties related to the Springer resolution of the nilpotent cone. In particular, we describe explicitly the action of the Artin braid group. This action is a “categorical version” of Kazhdan-Lusztig-Ginzburg’s construction of the affine Hecke algebra, and is used in particular by the first author and I. Mirković in the course...
Algebraic monoids with a dense group of units.
Analyse spectrale des fonctions modulaires
Commutators in certain nilpotent linear groups
Compactification via le spectre réel d’espaces des classes de représentation dans SO
Soit un groupe de type fini non élémentaire. On note l’ensemble des structures hyperboliques de dimension sur . peut se réaliser comme fermé dans un espace semi-algébrique qui admet une compactification naturelle par le spectre réel. On note le compactifié via le réel de . L’objet de cet article est de décrire les points ajoutés dans . La compactification obtenue de cette manière permet d’interpréter “les points frontières” comme des représentations de dans où est un corps réel...
Connected algebraic monoids.
Contractions of Lie algebras and algebraic groups
Degenerations, contractions and deformations of various algebraic structures play an important role in mathematics and physics. There are many different definitions and special cases of these notions. We try to give a general definition which unifies these notions and shows the connections among them. Here we focus on contractions of Lie algebras and algebraic groups.
Covariants under the full linear group
Cyclotomic equations and square properties in rings.
Das Relationenproblem für eine Klasse von Untergruppen orthogonaler Gruppen.
Definition einer Dixmier-Abbildung für ? l(n, C).
Développements récents sur les groupes de tresses. Applications à la topologie et à l'algèbre
Genus sets and SNT sets of certain connective covering spaces
We study the genus and SNT sets of connective covering spaces of familiar finite CW-complexes, both of rationally elliptic type (e.g. quaternionic projective spaces) and of rationally hyperbolic type (e.g. one-point union of a pair of spheres). In connection with the latter situation, we are led to an independently interesting question in group theory: if f is a homomorphism from Gl(ν,A) to Gl(n,A), ν < n, A = ℤ, resp. , does the image of f have infinite, resp. uncountably infinite, index in...
Hilbert's Fourteenth Problem for Non-Reductive Groups.
Les nombres de Tamagawa de groupes semi-simples
Linearizing some actions on affine space
Möbius inversion for the Bruhat ordering on a Weyl group
Naive boundary strata and nilpotent orbits
We give a Hodge-theoretic parametrization of certain real Lie group orbits in the compact dual of a Mumford-Tate domain, and characterize the orbits which contain a naive limit Hodge filtration. A series of examples are worked out for the groups , , and .