Journal Article F-rationality of the ring of modular invariants

Hashimoto, Mitsuyasu

484pp.207 - 223 , 2017-08-15 , Elsevier
ISSN:0021-8693
NCID:AA00692420
Description
Using the description of the Frobenius limit of modules over the ring of invariants under an action of a finite group on a polynomial ring over a field of characteristic p>0 developed by Symonds and the author, we give a characterization of the ring of invariants with a positive dual F-signature. Combining this result and Kemper's result on depths of the ring of invariants under an action of a permutation group, we give an example of an F-rational, but non-F-regular ring of invariants under the action of a finite group.

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