English

Dual of the Geometric Lemma and the Second Adjointness Theorem for $p$-adic reductive groups

Representation Theory 2026-01-05 v3 Number Theory

Abstract

Let P,QP,Q be standard parabolic subgroups of a pp-adic reductive group GG. We study the smooth dual of the filtration on a parabolically induced module arising from the geometric lemma associated to the cosets PG/QP\setminus G/Q. We prove that the dual filtration coincides with the filtration associated to the cosets PG/QP\setminus G/Q^- via the Bernstein-Casselman canonical pairing from the second adjointness of parabolic induction. This result generalizes a result of Bezrukavnikov-Kazhdan on the explicit description in the second adjointness. Along the way, we also study some group theoretic results.

Keywords

Cite

@article{arxiv.2406.13546,
  title  = {Dual of the Geometric Lemma and the Second Adjointness Theorem for $p$-adic reductive groups},
  author = {Kei Yuen Chan},
  journal= {arXiv preprint arXiv:2406.13546},
  year   = {2026}
}

Comments

20 pages, comments welcome, v2: fixed some typos, v3: minor corrections