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arXiv · 1802.06377

On the structure of affine flat group schemes over discrete valuation rings, II

Phùng Hô Hai·João Pedro dos Santos
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Abstract

In the 1st part of this work [DHdS18], we studied affine group schemes over a discrete valuation ring (DVR) by means of Neron blowups. We also showed how to apply these findings to throw light on the group schemes coming from Tannakian categories of D-modules. In the present work, we follow up this theme. We show that a certain class of affine group schemes of "infinite type", Neron blowups of formal subgroups, are quite typical. We also explain how these group schemes appear naturally in Tannakian categories of D-modules. To conclude, we isolate a Tannakian property of affine group schemes, named prudence, which allows one to verify if the underlying ring of functions is a free module over the base ring. This is then successfully applied to obtain a general result on the structure of differential Galois groups over complete DVRs.

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Phùng Hô Hai, João Pedro dos Santos. 2018-02-18. On the structure of affine flat group schemes over discrete valuation rings, II. https://doi.org/10.1093/imrn%2Frnaa247

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