An integral comparison of crystalline and de Rham cohomology

Fuente: arXiv
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Main Authors: Abhinandan, Youcis, Alex
Format: Preprint
Published: 2025
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author Abhinandan
Youcis, Alex
author_facet Abhinandan
Youcis, Alex
contents Let $\mathcal{O}_K$ be a mixed characteristic complete DVR with perfect residue field $k$ and fraction field $K$. It is a celebrated result of Berthelot and Ogus that for a smooth proper formal scheme $X/\mathcal{O}_K$ there exists a comparison between the de Rham cohomology groups $\mathrm{H}^i_\mathrm{dR}(X/\mathcal{O}_K)$ and the crystalline cohomology groups $\mathrm{H}^i_\mathrm{crys}(X_k/W(k))$ of the special fibre, after tensoring with $K$. In this article, we use the stacky perspective on prismatic cohomology, due to Drinfeld and Bhatt--Lurie, to give a version of this comparison result with coefficients in a perfect complex of prismatic $F$-crystals on $X$. Our method is of an integral nature and suggests new tools to understand the relationship between torsion in de Rham and crystalline cohomology.
format Preprint
id arxiv_https___arxiv_org_abs_2507_17631
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An integral comparison of crystalline and de Rham cohomology
Abhinandan
Youcis, Alex
Number Theory
Algebraic Geometry
14F30, 14F40
Let $\mathcal{O}_K$ be a mixed characteristic complete DVR with perfect residue field $k$ and fraction field $K$. It is a celebrated result of Berthelot and Ogus that for a smooth proper formal scheme $X/\mathcal{O}_K$ there exists a comparison between the de Rham cohomology groups $\mathrm{H}^i_\mathrm{dR}(X/\mathcal{O}_K)$ and the crystalline cohomology groups $\mathrm{H}^i_\mathrm{crys}(X_k/W(k))$ of the special fibre, after tensoring with $K$. In this article, we use the stacky perspective on prismatic cohomology, due to Drinfeld and Bhatt--Lurie, to give a version of this comparison result with coefficients in a perfect complex of prismatic $F$-crystals on $X$. Our method is of an integral nature and suggests new tools to understand the relationship between torsion in de Rham and crystalline cohomology.
title An integral comparison of crystalline and de Rham cohomology
topic Number Theory
Algebraic Geometry
14F30, 14F40
url https://arxiv.org/abs/2507.17631