p-adic deformations of cohomology classes of subgroups of GL (N,Z).
Let be a preprojective algebra of type , and let be the corresponding semisimple simply connected complex algebraic group. We study rigid modules in subcategories for an injective -module, and we introduce a mutation operation between complete rigid modules in . This yields cluster algebra structures on the coordinate rings of the partial flag varieties attached to .
Soient un corps -adique, . Pour un caractère de l’algèbre de Hecke sphérique de sur un anneau commutatif , on introduit à la suite de Serre une représentation lisse de sur qui gouverne la théorie des représentations non ramifiées de sur . Nous prouvons que est plat sur et que si est inversible dans , alors pour tout sous-groupe compact ouvert suffisament petit de , le module est libre de rang fini sur . Ceci était conjecturé par Lazarus. Comme corollaire, nous obtenons...
Given a tuple of irreducible characters of we define a star-shaped quiver together with a dimension vector . Assume that is generic. Our first result is a formula which expresses the multiplicity of the trivial character in the tensor product as the trace of the action of some Weyl group on the intersection cohomology of some (non-affine) quiver varieties associated to . The existence of such a quiver variety is subject to some condition. Assuming that this condition is satisfied, we...
The cohomology of Nakajima’s varieties is known to carry a natural Weyl group action. Here this fact is established using the method of intersection cohomology, in analogy with the definition of Springer’s representations.