2018/01/09 by Dong Uk Lee, Lee, Dong Uk
Mathematics · #Advanced Algebra and Geometry #Algebraic Geometry (math.AG) #Algebraic Geometry and Number Theory #FOS: Mathematics #Geometry and complex manifolds #Number Theory (math.NT) #math.AG #math.NT
paper · pdf · doi:10.48550/arxiv.1801.03057
162pages. A part of this work replaces our earlier work "arXiv:1603.04831v1" whose errors are fixed here
openalex publication_date 2018/01/09 · arxiv created 2018/05/30 · arxiv updated 2018/05/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
For any Shimura variety of Hodge type with hyperspecial level at a prime p and a lisse sheaf on it, we prove a formula, conjectured by Kottwitz \citeKottwitz90, for the Lefschetz number of an arbitrary Frobenius-twisted Hecke correspondence acting on the compactly supported étale cohomology and verify another conjecture of Kottwitz \citeKottwitz90 on the stabilization of that formula. The main ingredients of our proof of the formula are a recent work of Kisin \citeKisin17 on Langlands-Rapoport conjecture and the theory of Galois gerbs developed by Langlands and Rapoport \citeLR87. Especially, we use the Galois gerb theory to establish an effectivity criterion of Kottwitz triple, and mimic the arguments of Langlands and Rapoport of deriving the Kottwitz formula from their conjectural description of the \Fpb-point set of Shimura variety (Langlands-Rapoport conjecture). We do not assume that the derived group is simply connected, and also obtain partial results at (special) parahoric levels under some condition at p. For that, in the first part of our work we extend the results of Langlands and Rapoport to such general cases.