arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1606.01795math.RTmath.AG
收藏

半无限Deligne-Lusztig簇的上同调

The cohomology of semi-infinite Deligne--Lusztig varieties

Charlotte Chan

摘要:

证明了Lusztig在1979年提出的关于局部域上除代数的半无限Deligne-Lusztig簇的上同调猜想.我们还证明了Boyarchenko在这些品种上的两个证明。已知在这种情况下,半无限Deligne-Lusztig变种是由某些有限型格式$X_h$的极限组成的ind-格式。Boyarchenko的两个定理是关于$X_h$的极大性和关于它们的上同调的环面特征空间的行为。这两个代数都是众所周知的,在充分的一般性只为司代数与哈塞不变$1/n$的情况下,$h = 2$(“最低水平”)的工作Boyarchenko-温斯坦的上同调的一个特殊仿射的鲁宾-泰特塔。证明了$X_h$的有理点达到Weil-Deligne界,从而在很强的意义下,$X_h$的上同调是纯的.我们证明了$H_c^i(X_h)$的环面特征空间是不可约表示,并且恰好在一个上同调度上被支撑.最后,我们给出了半无限Deligne-Lusztig簇的同调群的完整刻画,从而给出了这些群的非分歧超尖点表示的几何实现.我们希望本文所发展的技术将有助于研究这些结构的约化群在局部域一般。

英文摘要:

We prove a 1979 conjecture of Lusztig on the cohomology of semi-infinite Deligne--Lusztig varieties attached to division algebras over local fields. We also prove the two conjectures of Boyarchenko on these varieties. It is known that in this setting, the semi-infinite Deligne--Lusztig varieties are ind-schemes comprised of limits of certain finite-type schemes $X_h$. Boyarchenko's two conjectures are on the maximality of $X_h$ and on the behavior of the torus-eigenspaces of their cohomology. Both of these conjectures were known in full generality only for division algebras with Hasse invariant $1/n$ in the case $h = 2$ (the "lowest level") by the work of Boyarchenko--Weinstein on the cohomology of a special affinoid in the Lubin--Tate tower. We prove that the number of rational points of $X_h$ attains its Weil--Deligne bound, so that the cohomology of $X_h$ is pure in a very strong sense. We prove that the torus-eigenspaces of $H_c^i(X_h)$ are irreducible representations and are supported in exactly one cohomological degree. Finally, we give a complete description of the homology groups of the semi-infinite Deligne--Lusztig varieties attached to any division algebra, thus giving a geometric realization of the unramified supercuspidal representations of these groups. We expect that the techniques developed in this paper will be useful in studying these constructions for reductive groups over local fields in general.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑