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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…

Algebraic Geometry · Mathematics 2016-11-01 Kento Fujita , Yuji Odaka

We define the relative stability threshold of a family of Fano varieties over a DVR and show that it is computed by a divisorial valuation. In the case when the special fiber is K-unstable, but the generic fiber is K-semistable, we use the…

Algebraic Geometry · Mathematics 2025-10-08 Harold Blum , Yuchen Liu , Chenyang Xu , Ziquan Zhuang

We generalise partial results about the Yau-Tian-Donaldson correspondence on ruled manifolds to bundles whose fibre is a classical flag variety. This is done using Chern class computations involving the combinatorics of Schur functors. The…

Algebraic Geometry · Mathematics 2015-11-11 Anton Isopoussu

We study Diophantine arithmetic properties of birational divisors in conjunction with concepts that surround $\mathrm{K}$-stability for Fano varieties. There is also an interpretation in terms of the barycentres of Newton-Okounkov bodies.…

Algebraic Geometry · Mathematics 2020-02-14 Nathan Grieve

We prove that on any log Fano pair of dimension $n$ whose stability threshold is less than $\frac{n+1}{n}$, any valuation computing the stability threshold has a finitely generated associated graded ring. Together with earlier works, this…

Algebraic Geometry · Mathematics 2022-02-15 Yuchen Liu , Chenyang Xu , Ziquan Zhuang

In this note, we adapt the Keevash-Sudakov proof of the (Tur\'{a}n) Stability Theorem for the Fano plane to find an explicit dependency between the parameters $\varepsilon$ and $\delta$. This is useful in the solution of a multicolored…

Combinatorics · Mathematics 2020-04-27 Carlos Hoppen , Hanno Lefmann , Knut Odermann

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

For any flat projective family $(\mX,\mL)\rightarrow C$ such that the generic fibre $\mX_\eta$ is a klt Q-Fano variety and $\mL|_{\mX_\eta}\sim_{Q}-K_{X_{\eta}}$, we use the techniques from the minimal model program (MMP) to modify the…

Algebraic Geometry · Mathematics 2013-10-15 Chi Li , Chenyang Xu

We introduce a theory of uniform K-stability for big line bundles on smooth projective varieties. This extends the existing theory both for varieties with ample line bundles, and for varieties with big anticanonical class. Our main result…

Algebraic Geometry · Mathematics 2026-03-27 Ruadhaí Dervan , Rémi Reboulet

We prove the following result: if a $\mathbb{Q}$-Fano variety is uniformly K-stable, then it admits a K\"{a}hler-Einstein metric. We achieve this by modifying Berman-Boucksom-Jonsson's strategy with appropriate perturbative arguments and…

Differential Geometry · Mathematics 2021-03-30 Chi Li , Gang Tian , Feng Wang

We present some applications of the deformation theory of toric Fano varieties to K-(semi/poly)stability of Fano varieties. First, we present two examples of K-polystable toric Fano 3-fold with obstructed deformations. In one case, the…

Algebraic Geometry · Mathematics 2021-09-02 Anne-Sophie Kaloghiros , Andrea Petracci

We give a purely algebro-geometric proof that if the alpha-invariant of a Q-Fano variety X is greater than dim X/(dim X+1), then (X,O(-K_X)) is K-stable. The key of our proof is a relation among the Seshadri constants, the alpha-invariant…

Algebraic Geometry · Mathematics 2012-08-10 Yuji Odaka , Yuji Sano

Let X be a normal complex projective variety with at worst klt singularities, and L a big line bundle on X. We use valuations to study the log canonical threshold of L, as well as another invariant, the stability threshold. The latter…

Algebraic Geometry · Mathematics 2020-02-11 Harold Blum , Mattias Jonsson

We prove a criterion for K-stability of a $\mathbb{Q}$-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…

Algebraic Geometry · Mathematics 2020-09-16 Thibaut Delcroix

We revisit Spakula's uniform K-homology, construct the external product for it and use this to deduce homotopy invariance of uniform K-homology. We define uniform K-theory and on manifolds of bounded geometry we give an interpretation of it…

K-Theory and Homology · Mathematics 2018-08-27 Alexander Engel

Let X be a Fano manifold. G.Tian proves that if X admits a Kaehler-Einstein metric, then it satisfies two different stability conditions: one involving the Futaki invariant of a special degeneration of X, the other Hilbert-Mumford-stability…

Algebraic Geometry · Mathematics 2007-05-23 Thomas Rudolf Bauer

We study the Fano scheme of $k$-planes contained in the hypersurface cut out by a generic sum of products of linear forms. In particular, we show that under certain hypotheses, linear subspaces of sufficiently high dimension must be…

Algebraic Geometry · Mathematics 2019-11-25 Nathan Ilten , Hendrik Süß

The main result of this paper is the following: for all $b \in \mathbb Z$ there exists $k=k(b)$ such that \[ \max \{ |A^{(k)}|, |(A+u)^{(k)}| \} \geq |A|^b, \] for any finite $A \subset \mathbb Q$ and any non-zero $u \in \mathbb Q$. Here,…

Number Theory · Mathematics 2020-09-22 Brandon Hanson , Oliver Roche-Newton , Dmitrii Zhelezov

In this note, we discuss a number of open problems in K-stability theory.

Algebraic Geometry · Mathematics 2026-01-23 Chenyang Xu , Ziquan Zhuang

kk$^{\text{ban}}$ is a bivariant K-theory for Banach algebras that has reasonable homological properties, a product and is Morita invariant in a very general sense. We define it here by a universal property and ensure its existence in a…

K-Theory and Homology · Mathematics 2014-06-10 Walther Paravicini