English

Types and collapse for cuspidal representations of groups acting on trees

Representation Theory 2026-07-30 v1 Number Theory

Abstract

In a previous paper, the second author proved that every supercuspidal representation of a rank-one p-adic group is induced from a compact-mod-center open subgroup. The method was geometric, localizing representations to obtain equivariant sheaves on trees. Here we provide two refinements. The first is a geometric description of the inducing data, via a geometrically minimal K-type. Second is a proof that the equivariant sheaves collapse onto injective sheaves. The two notions of geometrically minimal K-types and collapsibility generalize to higher rank groups, suggesting a pair of conjectures.

Cite

@article{arxiv.2607.27590,
  title  = {Types and collapse for cuspidal representations of groups acting on trees},
  author = {Samuel Johnson and Martin H. Weissman},
  journal= {arXiv preprint arXiv:2607.27590},
  year   = {2026}
}

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26 pages