12,860 research outputs found

    Purity results for pp-divisible groups and abelian schemes over regular bases of mixed characteristic

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    Let pp be a prime. Let (R,\ideal{m}) be a regular local ring of mixed characteristic (0,p)(0,p) and absolute index of ramification ee. We provide general criteria of when each abelian scheme over \Spec R\setminus\{\ideal{m}\} extends to an abelian scheme over \Spec R. We show that such extensions always exist if e≤p−1e\le p-1, exist in most cases if p≤e≤2p−3p\le e\le 2p-3, and do not exist in general if e≥2p−2e\ge 2p-2. The case e≤p−1e\le p-1 implies the uniqueness of integral canonical models of Shimura varieties over a discrete valuation ring OO of mixed characteristic (0,p)(0,p) and index of ramification at most p−1p-1. This leads to large classes of examples of N\'eron models over OO. If p>2p>2 and index p−1p-1, the examples are new.Comment: 28 pages. Final version identical (modulo style) to the galley proofs. To appear in Doc. Mat

    Families of p-divisible groups with constant Newton polygon

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    A p-divisible group over a base scheme in characteristic p in general does not admit a slope filtration. Let X be a p-divisible group with constant Newton polygon over a normal noetherian scheme S; we prove that there exists an isogeny from X to Y such that Y admits a slope filtration. In case S is regular this was proved by N. Katz for dim(S) = 1 and by T. Zink for dim(S) > 0. We give an example of a p-divisible group over a non-normal base which does not admit an isogeny to a p-divisible group with a slope filtration.Comment: To be published in Documenta Mathematic

    On the Drinfeld moduli problem of p-divisible groups

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    Let ODO_D be the ring of integers in a division algebra of invariant 1/n1/n over a p-adic local field. Drinfeld proved that the moduli problem of special formal ODO_D-modules is representable by Deligne's formal scheme version of the Drinfeld p-adic halfspace. In this paper we exhibit other moduli spaces of formal pp-divisible groups which are represented by pp-adic formal schemes whose generic fibers are isomorphic to the Drinfeld p-adic halfspace. We also prove an analogue concerning the Lubin-Tate moduli space.Comment: Expanded introductio

    EPVs: lists for evaluation of pragmatic skills

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