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Cofinal types of topological directed orders

SŁawomir Solecki, Stevo Todorcevic (2004)

Annales de l’institut Fourier

We investigate the structure of the Tukey ordering among directed orders arising naturally in topology and measure theory.

Coherent sheaves with parabolic structure and construction of Hecke eigensheaves for some ramified local systems

Jochen Heinloth (2004)

Annales de l'Institut Fourier

The aim of these notes is to generalize Laumon’s construction [20] of automorphic sheaves corresponding to local systems on a smooth, projective curve C to the case of local systems with indecomposable unipotent ramification at a finite set of points. To this end we need an extension of the notion of parabolic structure on vector bundles to coherent sheaves. Once we have defined this, a lot of arguments from the article “ On the geometric Langlands conjecture” by Frenkel, Gaitsgory and Vilonen [11]...

Cohomology of Drinfeld symmetric spaces and Harmonic cochains

Yacine Aït Amrane (2006)

Annales de l’institut Fourier

Let K be a non-archimedean local field. This paper gives an explicit isomorphism between the dual of the special representation of G L n + 1 ( K ) and the space of harmonic cochains defined on the Bruhat-Tits building of G L n + 1 ( K ) , in the sense of E. de Shalit [11]. We deduce, applying the results of a paper of P. Schneider and U. Stuhler [9], that there exists a G L n + 1 ( K ) -equivariant isomorphism between the cohomology group of the Drinfeld symmetric space and the space of harmonic cochains.

Cohomology of G / P for classical complex Lie supergroups G and characters of some atypical G -modules

Ivan Penkov, Vera Serganova (1989)

Annales de l'institut Fourier

We compute the unique nonzero cohomology group of a generic G 0 - linearized locally free 𝒪 -module, where G 0 is the identity component of a complex classical Lie supergroup G and P G 0 is an arbitrary parabolic subsupergroup. In particular we prove that for G ( m ) , S ( m ) this cohomology group is an irreducible G 0 -module. As an application we generalize the character formula of typical irreducible G 0 -modules to a natural class of atypical modules arising in this way.

Combinatorial and group-theoretic compactifications of buildings

Pierre-Emmanuel Caprace, Jean Lécureux (2011)

Annales de l’institut Fourier

Let X be a building of arbitrary type. A compactification 𝒞 sph ( X ) of the set Res sph ( X ) of spherical residues of X is introduced. We prove that it coincides with the horofunction compactification of Res sph ( X ) endowed with a natural combinatorial distance which we call the root-distance. Points of 𝒞 sph ( X ) admit amenable stabilisers in Aut ( X ) and conversely, any amenable subgroup virtually fixes a point in 𝒞 sph ( X ) . In addition, it is shown that, provided Aut ( X ) is transitive enough, this compactification also coincides with the group-theoretic...

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