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We compute global log canonical thresholds of certain birationally bi-rigid Fano 3-folds embedded in weighted projective spaces as complete intersections of codimension 2 and prove that they admit an orbifold K\"{a}hler-Einstein metric and…

Algebraic Geometry · Mathematics 2019-03-19 In-Kyun Kim , Takuzo Okada , Joonyeong Won

We study log canonical thresholds on quartic threefolds, quintic fourfolds, and double spaces. As an application, we show that they have a Kaehler-Einstein metric if they are general.

Algebraic Geometry · Mathematics 2015-01-05 Ivan Cheltsov , Jihun Park , Joonyeong Won

We study global log canonical thresholds on anticanonically embedded quasismooth weighted Fano threefold hypersurfaces having terminal quotient singularities to prove the existence of a Kahler-Einstein metric on most of them, and to produce…

Algebraic Geometry · Mathematics 2007-06-18 Ivan Cheltsov

We compute global log canonical thresholds of some smooth Fano threefolds.

Algebraic Geometry · Mathematics 2009-02-08 Ivan Cheltsov , Constantin Shramov

We give an elementary argument to compute the $\alpha$-invariant of this Fano 3-fold, which implies the existence of a Kahler-Einstein metric.

Differential Geometry · Mathematics 2007-11-29 S. K. Donaldson

We provide a sufficient condition for polarisations of Fano varieties to be K-stable in terms of Tian's alpha invariant, which uses the log canonical threshold to measure singularities of divisors in the linear system associated to the…

Algebraic Geometry · Mathematics 2016-04-21 Ruadhaí Dervan

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…

Algebraic Geometry · Mathematics 2013-08-13 Hendrik Süß

The global log canonical threshold (or Tian's alpha-invariant) plays an important role in the geometry of Fano varieties. Tian showed that Fano manifolds with big alpha-invariant can be equipped with a Kahler-Einstein metric. In recent…

Algebraic Geometry · Mathematics 2013-09-06 Jesus Martinez-Garcia

In this paper, we study the explicit geometry of threefolds, in particular, Fano varieties. We find an explicitly computable positive integer $N$, such that all but a bounded family of Fano threefolds have $N$-complements. This result has…

Algebraic Geometry · Mathematics 2023-11-14 Caucher Birkar , Jihao Liu

We generalize the definition of alpha invariant to arbitrary codimension. We also give a lower bound of these alpha invariants for K-semistable Q-Fano varieties and show that we can characterize projective spaces among all K-semistable Fano…

Algebraic Geometry · Mathematics 2020-01-28 Ziwen Zhu

We prove that the alpha invariant of a quasi-smooth Fano 3-fold weighted hypersurface of index $1$ is greater than or equal to $1/2$. Combining this with the result of Stibitz and Zhuang \cite{SZ19} on a relation between birational…

Algebraic Geometry · Mathematics 2023-08-29 In-Kyun Kim , Takuzo Okada , Joonyeong Won

We give a criterion for the existence of a K\"ahler-Einstein metric on a Fano manifold $M$ in terms of the higher algebraic alpha-invariants $\alpha_{m,k}(M)$.

Differential Geometry · Mathematics 2014-12-02 Heather Macbeth

We show that any $n$-dimensional Fano manifold $X$ with $\alpha(X)=n/(n+1)$ and $n\geq 2$ is K-stable, where $\alpha(X)$ is the alpha invariant of $X$ introduced by Tian. In particular, any such $X$ admits K\"ahler-Einstein metrics and the…

Algebraic Geometry · Mathematics 2016-06-28 Kento Fujita

We compute global log canonical thresholds of a large class of quasismooth well-formed del Pezzo weighted hypersurfaces in $\mathbb{P}(a_{1},a_{2},a_{3},a_{4})$. As a corollary we obtain the existence of orbifold K\"ahler--Einstein metrics…

Algebraic Geometry · Mathematics 2009-04-06 Ivan Cheltsov , Jihun Park , Constantin Shramov

Given a Fano manifold $(X,\omega)$ we develop a variational approach to characterize analytically the existence of K\"ahler-Einstein metrics with prescribed singularities, assuming that these singularities can be approximated algebraically.…

Differential Geometry · Mathematics 2023-09-21 Antonio Trusiani

It was conjectured by Tian that the global log canonical threshold (known as the $\alpha$-invariant) is equal to the level $k$ log canonical threshold (known as the $\alpha_k$-invariant) for all sufficiently large $k$. A weaker folklore…

Algebraic Geometry · Mathematics 2024-12-04 Chenzi Jin

We give conditions for a uniruled variety of dimension at least 2 to be non-solid. This study provides further evidence to a conjecture by Abban and Okada on the solidity of Fano 3-folds. To complement our results we write explicit…

Algebraic Geometry · Mathematics 2023-07-07 Livia Campo , Tiago Duarte Guerreiro

The global holomorphic \alpha-invariant introduced by Tian is closely related with the study in the existence of Kahler-Einstein metric. We apply the result of Tian, Lu and Zelditch on polarized Kahler metrics to approximate…

Differential Geometry · Mathematics 2007-05-23 Jian Song

We prove that every birationally superrigid Fano variety whose alpha invariant is greater than (resp. no smaller than) $\frac{1}{2}$ is K-stable (resp. K-semistable). We also prove that the alpha invariant of a birationally superrigid Fano…

Algebraic Geometry · Mathematics 2019-08-15 Charlie Stibitz , Ziquan Zhuang

We give a criterion for the coercivity of the Mabuchi functional for general K\"ahler classes on Fano manifolds in terms of Tian's alpha invariant. This generalises a result of Tian in the anti-canonical case implying the existence of a…

Differential Geometry · Mathematics 2016-04-19 Ruadhaí Dervan
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