On typical representations for depth-zero components of split classical groups

TL;DR

This paper classifies certain depth-zero representations of split classical groups over non-Archimedean fields, showing they are precisely the irreducible subrepresentations of specific induced representations, advancing understanding of local representation theory.

Contribution

It provides a complete classification of -typical representations of hyperspecial maximal compact subgroups in split classical groups, linking them to level-zero G-covers of Levi subgroup types.

Findings

-typical representations are irreducible subrepresentations of induced representations.

The classification applies to groups over fields with residue characteristic greater than 5.

It connects -typical representations to Moy--Prasad types and G-covers.

Abstract

Let ${\bf G}$ be a split classical group over a non-Archimedean local field $F$ with the cardinality of the residue field $q_F>5$. Let $M$ be the group of $F$-points of a Levi factor of a proper $F$-parabolic subgroup of ${\bf G}$. Let $[M, \sigma_M]_M$ be an inertial class such that $\sigma_M$ contains a depth-zero Moy--Prasad type of the form $(K_M, \tau_M)$, where $K_M$ is a hyperspecial maximal compact subgroup of $M$. Let $K$ be a hyperspecial maximal compact subgroup of ${\bf G}(F)$ such that $K$ contains $K_M$. In this article, we classify $\mathfrak{s}$-typical representations of $K$. In particular, we show that the $\mathfrak{s}$-typical representations of $K$ are precisely the irreducible subrepresentations of $\ind_J^K\lambda$, where $(J, \lambda)$ is a level-zero $G$-cover of $(K\cap M, \tau_M)$.