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Search options not deleted user 4008
7 votes
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Cartier dual of \alpha_p

It is probably a bad idea to try to compute the Cartier dual but better to let Cartier do that for you... If $G$ is a flat commutative finite group scheme with affine algebra, the commutative and coco …
Torsten Ekedahl's user avatar
21 votes

Automorphism group of a scheme

The automorphism group functor is not representable in general. Consider for instance the case of an algebraically closed field $k$ and $\mathbf A^2=\mathrm{Spec}\ k[x,y]$. Assume the automorphism gro …
Torsten Ekedahl's user avatar
1 vote

Smooth linear algebraic groups over the dual numbers

I don't understand why the usual proof over a field base doesn't work over a (local) artinian base $R$ for a flat finite type group scheme over $R$: Let $A$ be the affine algebra of $G$. Take any basi …