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Test configurations and Okounkov bodies

Published online by Cambridge University Press:  11 October 2012

David Witt Nyström*
Affiliation:
Chalmers University of Technology and University of Göteborg, Göteborg, Sweden (email: wittnyst@chalmers.se)
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Abstract

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We associate to a test configuration for a polarized variety a filtration of the section ring of the line bundle. Using the recent work of Boucksom and Chen we get a concave function on the Okounkov body whose law with respect to Lebesgue measure determines the asymptotic distribution of the weights of the test configuration. We show that this is a generalization of a well-known result in toric geometry. As an application, we prove that the pushforward of the Lebesgue measure on the Okounkov body is equal to a Duistermaat–Heckman measure of a certain deformation of the manifold. Via the Duisteraat–Heckman formula, we get as a corollary that in the special case of an effective ℂ×-action on the manifold lifting to the line bundle, the pushforward of the Lebesgue measure on the Okounkov body is piecewise polynomial.

Type
Research Article
Copyright
Copyright © Foundation Compositio Mathematica 2012

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