# Institut for Matematik

## Geometry of BxB-orbit closures in equivariant embeddings

Publikation: Working paper/Preprint Working paperForskning

• Institut for Matematiske Fag
Let X denote an equivariant embedding of a connected reductive group G over an algebraically closed field k. Let B denote a Borel subgroup of G and let Z denote a BxB-orbit closure in X. When the characteristic of k is positive and X is projective we prove that Z is globally F-regular. As a consequence, Z is normal and Cohen-Macaulay for arbitrary X and arbitrary characteristics. Moreover, in characteristic zero it follows that Z has rational singularities. This extends earlier results by the second author and M. Brion.
Originalsprog Engelsk 20 Udgivet - 2005

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