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arXiv · 1204.1729

Principal bundles of reductive groups over affine schemes

Ivan Panin·Anastasia Stavrova
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Abstract

Let R be a semi-local regular domain containing an infinite perfect field k, and let K be the field of fractions of R. Let G be a reductive semi-simple simply connected R-group scheme such that each of its R-indecomposable factors is isotropic. We prove that for any Noetherian affine scheme A over k, the kernel of the map of etale cohomology sets H^1(A\times_k R,G)-> H^1(A\times_ k K,G), induced by the inclusion of R into K, is trivial. If R is the semi-local ring of several points on a k-smooth scheme, then it suffices to require that k is infinite and keep the same assumption concerning G.

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Ivan Panin, Anastasia Stavrova. 2012-04-08. Principal bundles of reductive groups over affine schemes. https://arxiv.org/abs/1204.1729

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