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Iskovskikh Seminar
September 20, 2012 18:00, Moscow, Steklov Mathematical Institute, room 530
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Log-canonical thresholds under torus quotients
Hendrik Suss M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics
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Abstract:
The log-canonical threshold of a Fano variety $X$ is an invariant with
applications in birational geometry as well as in Kahler geometry. It is
defined with respect to a finite subgroup $G$ of $Aut(X)$. After chosing a
maximal torus $T$ in the automorphismen group of our Fano variety $X$ we
would like to reduce the computation of the log-canonical threshold on X
to that of a log-canonical threshold on some torus quotient $X=X/T$. As it
turns out, this works well if the following conditions are fulfilled:
(i) $G$ is contained in the normalizer of the maximal torus,
(ii) the $G$-action on the characters given by conjugation has the trivial
character as its unique fixed point.
In this situation the $T$-variety is called symmetric. As an application
we provide a criterion for the existence of Kahler–Einstein metrics on
symmetric Fano $T$-varieties of complexity one.
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