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A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

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4079119158 · Jun 202019922001200920172026
48 results for Fano variety

We prove that K-polystable degenerations of Q-Fano varieties are unique. Furthermore, we show that the moduli stack of K-stable Q-Fano varieties is separated. Together with [Jia17,BL18], the latter result yields a separated Deligne-Mumford stack parametrizing all uniformly K-stable Q-Fano varieties of fixed dimension a…

2018-12-09abs ↗pdf ↗

We prove the Yau-Tian-Donaldson's conjecture for any Q\mathbb{Q}-Fano variety that has a log smooth resolution of singularities such that the discrepancies of all exceptional divisors are non-positive. In other words, if such a Fano variety is K-polystable, then it admits a Kähler-Einstein metric. This extends the pre…

2017-11-27abs ↗pdf ↗

Classifies Fano varieties with large pseudoindex and non-free rational curves.

problem Classifying Fano varieties with specific properties.
method Extremal contractions and classification of varieties.
result Complete classification of Fano nn-folds with pseudoindex at least n2n-2 and Picard number greater than one.

We prove that every birationally superrigid Fano variety whose alpha invariant is greater than (resp. no smaller than) 12\frac{1}{2} is K-stable (resp. K-semistable). We also prove that the alpha invariant of a birationally superrigid Fano variety of dimension nn is at least 1n+1\frac{1}{n+1} (under mild assumptions) an…

2018-02-23abs ↗pdf ↗

The study finds Kähler-Einstein metrics on certain Fano varieties of type AIII.

problem Finding Kähler-Einstein metrics on specific Fano varieties.
method Using combinatorial criteria for K-polystability and properties of Fano varieties.
result Proves existence of Kähler-Einstein metrics on XmX_m for m4m \geq 4 and on YmY_m for m=4,5m = 4, 5.

Kähler-Einstein metrics found on special types of symmetric varieties.

problem Finding Kähler-Einstein metrics on smooth Fano symmetric varieties with specific properties.
method Used a combinatorial criterion for K-stability of Fano spherical varieties and computed algebraic moment polytopes and barycenters.
result Proved all smooth Fano symmetric varieties with Picard number one admit Kähler-Einstein metrics.

Decomposes Q-Fano Kähler-Einstein varieties into simpler components.

problem Understanding the structure of Q-Fano Kähler-Einstein varieties.
method Proves decomposition theorem using algebraically integrable foliations and stability conditions.
result Q-Fano Kähler-Einstein varieties decompose into simpler components.

Reverse Hölder inequalities on Fano metrics with applications to geodesics and singularities.

problem Establishing reverse Hölder inequalities on Kähler metrics of Fano varieties.
method Using log-concavity and properties of Ricci potentials, the inequality is proven for Fano manifolds with log terminal singularities.
result The inequality holds for Fano varieties with log terminal singularities and the constant depends only on p and the dimension of X.

In this paper, we consider the CM line bundle on the K-moduli space, i.e., the moduli space parametrizing K-polystable Fano varieties. We prove it is ample on any proper subspace parametrizing reduced uniformly K-stable Fano varieties which conjecturally should be the entire moduli space. As a corollary, we prove that …

2019-12-30abs ↗pdf ↗

We apply a recent theorem of Li and the first author to give some criteria for the K-stability of Fano varieties in terms of anticanonical Q-divisors. First, we propose a condition in terms of certain anticanonical Q-divisors of given Fano variety, which we conjecture to be equivalent to the K-stability. We prove that …

2016-02-03abs ↗pdf ↗

For any flat projective family $(\mX,\mL)\rightarrow C$ such that the generic fibre $\mX_η$ is a klt Q-Fano variety and $\mL|_{\mX_η}\sim_{Q}-K_{X_η}$, we use the techniques from the minimal model program (MMP) to modify the total family. The end product is a family such that every fiber is a klt Q-Fano variety. Moreov…

2011-11-23abs ↗pdf ↗

Unique K-polystable degenerations for Fano varieties confirmed.

problem Algebraic uniqueness of Kähler-Ricci flow limits on Fano manifolds.
method Study of optimal degeneration problems via new functionals of real valuations.
result Confirm algebraic uniqueness of Kähler-Ricci flow limits on Fano manifolds.

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…

2012-08-17abs ↗pdf ↗

Motivated by the study of Fano type varieties we define a new class of log pairs that we call asymptotically log Fano varieties and strongly asymptotically log Fano varieties. We study their properties in dimension two under an additional assumption of log smoothness, and give a complete classification of two dimension…

2013-08-12abs ↗pdf ↗

Study positive characteristic Fano 4-folds with nef tangent bundles.

problem Positive characteristic version of the Campana-Peternell conjecture for Fano 4-folds.
method Analyzes Fano 4-folds with nef tangent bundles in positive characteristic.
result Affirmative answer for Fano 4-folds with Picard number > 1 and nef tangent bundle.

Extends results on smoothability of singular Fano and Calabi-Yau varieties.

problem Smoothability of singular Fano and Calabi-Yau varieties under terminal singularities.
method Generalizes deformation theory results for Calabi-Yau and Fano threefolds to higher dimensions, using higher Du Bois and rational singularities.
result Identifies a class of singularities for which smoothing results hold, including generalized Fano and Calabi-Yau varieties.

We prove that K-polystable log Fano pairs have reductive automorphism groups. In fact, we deduce this statement by establishing more general results concerning the S-completeness and ΘΘ-reductivity of the moduli of K-semistable log Fano pairs. Assuming the conjecture that K-semistability is an open condition, we prove…

2019-06-07abs ↗pdf ↗

Sharp bounds on K-semistable Fano varieties for low dimensions.

problem Establishing bounds on the height of K-semistable Fano varieties.
method Analyzing canonical integral models of toric Fano varieties, using the gap hypothesis and Donaldson's modular height.
result Sharp lower bounds on the height of toric Fano varieties, with applications to Mabuchi functional and Odaka's modular height.

The notion of asymptotically log Fano varieties was given by Cheltsov and Rubinstein. We show that, if an asymptotically log Fano variety (X,D)(X, D) satisfies that DD is irreducible and KXD-K_X-D is big, then XX does not admit Kähler-Einstein edge metrics with angle 2πβ2πβ along DD for any sufficiently small positive ra…

2015-09-09abs ↗pdf ↗

Tian's criterion for K-stability states that a Fano variety of dimension nn whose alpha invariant is greater than nn+1\frac{n}{n+1} is K-stable. We show that this criterion is sharp by constructing singular Fano varieties with alpha invariants nn+1\frac{n}{n+1} that are not K-polystable for sufficiently large nn. We also…

2019-03-12abs ↗pdf ↗

We show that the anti-canonical volume of an nn-dimensional Kähler-Einstein Q\mathbb{Q}-Fano variety is bounded from above by certain invariants of the local singularities, namely lctnmult\mathrm{lct}^n\cdot\mathrm{mult} for ideals and the normalized volume function for real valuations. This refines a recent result by Fuji…

2016-05-03abs ↗pdf ↗

Study of Kähler-Ricci flow on toric Fano varieties with preserved symplectic condition.

problem Analyzing the generalized Kähler-Ricci flow on toric Fano varieties.
method Establishing global existence, deriving entropy and energy functionals.
result Convergence of nonsingular solutions at infinity and weak convergence of the flow.

The paper shows how certain complex projective varieties can be broken down into simpler types.

problem Understanding the structure of complex projective varieties with pseudo-effective tangent sheaves.
method Developed a theory of pseudo-effective sheaves and applied the minimal model program.
result Projective klt varieties with pseudo-effective tangent sheaves can be decomposed into Fano varieties and Q-abelian varieties.

Paper studies limits of Kähler-Ricci flow on Fano G-manifolds.

problem Analyzing the limits of Kähler-Ricci flow on Fano G-manifolds.
method Proves the Gromov-Hausdorff limit of Kähler-Ricci flow on Fano G-manifolds is a horosymmetric variety.
result The limit of Kähler-Ricci flow on Fano G-manifolds is a horosymmetric variety.

Kähler-Ricci flow on spherical Fano manifolds converges to a soliton.

problem Analyzing the behavior of Kähler-Ricci flow on spherical Fano manifolds.
method Gromov-Hausdorff limit and torus degeneration.
result The limit of Kähler-Ricci flow on spherical Fano manifolds is a spherical Fano variety with a Kähler-Ricci soliton.

We prove a criterion for K-stability of a Q\mathbb{Q}-Fano spherical variety with respect to equivariant special test configurations, in terms of its moment polytope and some combinatorial data associated to the open orbit. Combined with the equivariant version of the Yau-Tian-Donaldson conjecture for Fano manifolds p…

2016-08-05abs ↗pdf ↗

It is shown that any, possibly singular, Fano variety X admitting a Kahler-Einstein metric is K-polystable, thus confirming one direction of the Yau-Tian-Donaldson conjecture in the setting of Q-Fano varieties equipped with their anti-canonical polarization. The proof exploits convexity properties of the Ding functiona…

2012-05-28abs ↗pdf ↗

New examples of Kähler-Ricci solitons on Fano threefolds with non-trivial moduli found.

problem Finding Fano threefolds with Kähler-Ricci solitons and non-trivial moduli.
method Established weighted K-stability and GIT-stability criteria, generalized Koiso's theorem, and developed the weighted Abban-Zhuang estimate.
result First examples of strictly weighted K-semistable Fano varieties and new examples of KRS Fano varieties with non-trivial moduli and small automorphism groups.

The interpretation, due to T. Mabuchi, of the classical Futaki invariant of Fano toric manifolds is extended to the case of the Generalized Futaki invariant, introduced by W. Ding and G. Tian, of almost Fano toric varieties. As an application it is shown that the real part of the Generalized Futaki invariant is positiv…

1998-06-21abs ↗pdf ↗