Saturday, 3 October 2009

ag.algebraic geometry - A technical question about derivations of sheaves on group schemes

Let G be a group scheme (for instance, over k a field of characteristic 0).
Let e be its unit.
I denote by OG the structural sheaf of G.



Let De:OG,etok a derivation.



I would like to get directly (ie, without any consideration about the cotangent bundle, or some canonical isomorphisms...) a derivation D:OGtoOG that extends De, and which is compatible with the action of G. That is, I would like to get this derivation by the mean of the multiplication map : m:GtimesGtoG, etc., etc.



I have guessed this question would not be difficult, and would only be a matter of technics, but I can't manage to do it.

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