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Rational p-adic Hodge theory for d-de Rham-proper stacks
In this follow-up paper we show that smooth Hodge-proper stacks over O𝐾 are ℚ𝑝-locally acyclic: namely the natural map between étale ℚ𝑝-cohomology of the algebraic and Raynaud generic fibers is an equivalence. This establishes the ℚ𝑝-case of general conjectures made in D. Kubrak and A. Prikhodko [p-adic Hodge theory for Artin stacks, Mem. Amer. Math. Soc. 304 (2024), 1174]. As a corollary, we get that if a smooth Artin stack over K has a smooth Hodge-proper model over O𝐾, its ℚ𝑝-étale cohomology is a crystalline Galois representation. We then also establish a truncated version of the above results in more general setting of smooth d-de Rham-proper stacks over O𝐾: here we only require first d-de Rham cohomology groups be finitely generated over O𝐾. As an application, we deduce a certain purity-type statement for étale ℚ𝑝-cohomology of Raynaud generic fiber, as well as crystallinity of a first several étale cohomology groups in the presence of a Cohen–Macauley model over O𝐾 in the schematic setting.