English

Breuil's Lattice Conjecture for GL2(K)

Number Theory 2026-05-25 v2

Abstract

We prove Breuil's lattice conjecture for higher Hodge-Tate weights in the case of GL2(K)\mathrm{GL}_2(K) where KK is an unramified extension of Qp\mathbb{Q}_p. More precisely, under some genericity conditions, we show that the lattice inside a locally algebraic type induced by the completed cohomology of a U(2)U(2)-arithmetic manifold depends only on the Galois representation at places above pp for arbitrary Hodge-Tate weights, which are small relative to pp. We further prove that the patched modules of all lattices inside the locally algebraic types with irreducible cosocle are cyclic. One key input of the paper is a structure theorem for mod pp representations of GL2(OK)\mathrm{GL}_2(\mathcal{O}_K), which are residually multiplicity free and of finite length. Another input is an explicit computation of universal framed Galois deformation rings, which parameterize potentially crystalline lifts with fixed tame inertial types and higher Hodge-Tate weights.

Keywords

Cite

@article{arxiv.2512.00178,
  title  = {Breuil's Lattice Conjecture for GL2(K)},
  author = {Hymn Chan},
  journal= {arXiv preprint arXiv:2512.00178},
  year   = {2026}
}

Comments

72 pages, various corrections

R2 v1 2026-07-01T08:00:16.324Z