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arXiv · 1004.4205

An upper bound on the Abbes-Saito filtration for finite flat group schemes and applications

Yichao Tian
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Abstract

Let $\cO_K$ be a complete discrete valuation ring of residue characteristic $p>0$, and $G$ be a finite flat group scheme over $\cO_K$ of order a power of $p$. We prove in this paper that the Abbes-Saito filtration of $G$ is bounded by a simple linear function of the degree of $G$. Assume $\cO_K$ has generic characteristic 0 and the residue field of $\cO_K$ is perfect. Fargues constructed the higher level canonical subgroups for a Barsotti-Tate group $\cG$ over $\cO_K$ which is "not too supersingular". As an application of our bound, we prove that the canonical subgroup of $\cG$ of level $n\geq 2$ constructed by Fargues appears in the Abbes-Saito filtration of the $p^n$-torsion subgroup of $\cG$.

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Yichao Tian. 2010-05-17. An upper bound on the Abbes-Saito filtration for finite flat group schemes and applications. https://arxiv.org/abs/1004.4205

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