Cocharacter-closure and the rational Hilbert-Mumford Theorem

Michael Bate; Sebastian Herpel; Benjamin Martin; Gerhard Roehrle

doi:10.1007/s00209-016-1816-5

Cocharacter-closure and the rational Hilbert-Mumford Theorem

Michael Bate, Sebastian Herpel, Benjamin Martin, Gerhard Roehrle^* (Corresponding Author)

^*Corresponding author for this work

Mathematical Science

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13 Citations (Scopus)

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Abstract

For a field k, let G be a reductive k-group and V an affine k-variety on which G acts. Using the notion of cocharacter-closed G(k)-orbits in V , we prove a rational version of the celebrated Hilbert-Mumford Theorem from geometric invariant theory. We initiate a study of applications stemming from this rationality tool. A number of examples are discussed to illustrate the concept of cocharacter-closure and to highlight how it differs from the usual Zariski-closure.

Original language	English
Pages (from-to)	39-72
Number of pages	34
Journal	Mathematische Zeitschrift
Volume	287
Issue number	1-2
Early online date	10 Nov 2016
DOIs	https://doi.org/10.1007/s00209-016-1816-5
Publication status	Published - 1 Oct 2017

Bibliographical note

33 pages, v. 2 reference added, slight changes

The authors acknowledge the financial support of EPSRC Grant EP/L005328/1 and of Marsden Grants UOC1009 and UOA1021. Part of the research for this paper was carried out while the authors were staying at the Mathematical Research Institute Oberwolfach supported by the “Research in Pairs” programme. Also, part of this paper was written during mutual visits to Auckland, Bochum and York. We are grateful to the referees for their careful reading of the paper and for helpful suggestions.

Keywords

Affine G-variety
Cocharacter-closed orbit
Rationality

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10.1007/s00209-016-1816-5Licence: CC BY

Cocharacter-closure and the rational Hilbert–Mumford Theorem
© The Author(s) 2016 This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Final published version, 813 KBLicence: CC BY

http://arxiv.org/abs/1411.7849v2Licence: Unspecified

Ben Martin
- School of Natural & Computing Sciences, Mathematical Science - Personal Chair
Person: Academic

Cite this

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abstract = "For a field k, let G be a reductive k-group and V an affine k-variety on which G acts. Using the notion of cocharacter-closed G(k)-orbits in V , we prove a rational version of the celebrated Hilbert-Mumford Theorem from geometric invariant theory. We initiate a study of applications stemming from this rationality tool. A number of examples are discussed to illustrate the concept of cocharacter-closure and to highlight how it differs from the usual Zariski-closure.",

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N2 - For a field k, let G be a reductive k-group and V an affine k-variety on which G acts. Using the notion of cocharacter-closed G(k)-orbits in V , we prove a rational version of the celebrated Hilbert-Mumford Theorem from geometric invariant theory. We initiate a study of applications stemming from this rationality tool. A number of examples are discussed to illustrate the concept of cocharacter-closure and to highlight how it differs from the usual Zariski-closure.

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DO - 10.1007/s00209-016-1816-5

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JO - Mathematische Zeitschrift

JF - Mathematische Zeitschrift

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ER -

Cocharacter-closure and the rational Hilbert-Mumford Theorem

Abstract

Bibliographical note

Keywords

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