48,447 research outputs found
Kahler-Einstein metrics on symmetric Fano T-varieties
We relate the global log canonical threshold of a variety with torus action
to the global log canonical threshold of its quotient. We apply this to certain
Fano varieties and use Tian's criterion to prove the existence of
Kahler-Einstein metrics on them. In particular, we obtain simple examples of
Fano threefolds being Kahler-Einstein but admitting deformations without
Kahler-Einstein metric.Comment: 12 pages, main theorem slightly improved + minor correction
Normal singularities with torus actions
We propose a method to compute a desingularization of a normal affine variety
X endowed with a torus action in terms of a combinatorial description of such a
variety due to Altmann and Hausen. This desingularization allows us to study
the structure of the singularities of X. In particular, we give criteria for X
to have only rational, (QQ-)factorial, or (QQ-)Gorenstein singularities. We
also give partial criteria for X to be Cohen-Macaulay or log-terminal. Finally,
we provide a method to construct factorial affine varieties with a torus
action. This leads to a full classification of such varieties in the case where
the action is of complexity one.Comment: 23 page
Mutual coupling compensation in uniform circular arrays with center element using a coupling matrix based on phase modes
Saving the common hamster from extinction through the EU habitats directive : a mandatory recovery effort, a remediation of past non-compliance or an exercise in futility?
Shanks-transform accelerated PML-based series expansions for the 1-D periodic 3-D Green's functions of multilayered media
A PerfectlyMatched Layer (PML) based formalismis proposed to derive fast converging series expansions for the 1D periodic
3D Green’s functions of layered media. The Shanks transform is applied to accelerate the PML-based series
Ewald-transform accelerated PML-based series expansions for the 1-D periodic 3-D Green's functions of multilayered media
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