English

Automorphic congruences between torsion cohomological classes

Number Theory 2025-10-03 v3

Abstract

For two representations of some local division algebra, congruent modulo ll, giving rise to two Harris-Taylor local systems on the corresponding Newton strata of the special fiber of a KHT Shimura varieties, we prove that the ll-torsion of each of their cohomology groups with compact supports are isomorphic, or equivalently the free quotients of each of the cohomology groups are congruent modulo ll. We then deduce the construction of accurate non tempered automorphic congruences for a similitude group G/QG/\mathbb Q with signature (1,d1)(1,d-1).

Keywords

Cite

@article{arxiv.2201.06048,
  title  = {Automorphic congruences between torsion cohomological classes},
  author = {Boyer Pascal},
  journal= {arXiv preprint arXiv:2201.06048},
  year   = {2025}
}

Comments

correction of some typos

R2 v1 2026-06-24T08:51:33.869Z