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We compute Gromov-Witten invariants of any genus for del Pezzo surfaces of degree $\ge2$. The genus zero invariants have been computed a long ago, Gromov-Witten invariants of any genus for del Pezzo surfaces of degree $\ge3$ have been found…

代数几何 · 数学 2014-04-25 M. Shoval , E. Shustin

It is well known that there are totally 130 deformation families of quasi-smooth terminal weighted hypersurface Fano threefolds and all members belonging to 95 families of Fano indices one are birationally rigid. Among remaining $35$…

代数几何 · 数学 2025-09-09 In-Kyun Kim , Takashi Kishimoto , Joonyeong Won

It has been known that nonsingular Fano threefolds of Picard rank one with the anti-canonical degree 22 admitting faithful actions of the multiplicative group form a one-dimensional family. Cheltsov and Shramov showed that all but two of…

代数几何 · 数学 2021-07-13 Kento Fujita

It is known that a given smooth del Pezzo surface or Fano threefold $X$ admits a choice of log Calabi-Yau compactified mirror toric Landau-Ginzburg model (with respect to certain fixed K\"ahler classes and Gorenstein toric degenerations).…

代数几何 · 数学 2025-03-20 Jacopo Stoppa

This paper initiates the systematic study of the number of points of bounded height on symmetric squares of weak Fano varieties. We provide a general framework for establishing the point count on $\text{Sym}^2 X$. In the specific case of…

The purpose of this article is to develop techniques for estimating basis log canonical thresholds on logarithmic surfaces. To that end, we develop new local intersection estimates that imply log canonicity. Our main motivation and…

代数几何 · 数学 2024-11-22 Ivan A. Cheltsov , Yanir A. Rubinstein , Kewei Zhang

This note is a short survey on the Lefschetz defect, an invariant of smooth Fano varieties that has been recently introduced; it is related to the Picard number rho(X) of X, and to the Picard number of prime divisors in X. We explain the…

代数几何 · 数学 2022-12-09 Cinzia Casagrande

We prove new local inequality for divisors on surfaces and utilize it to compute $\alpha$-invariants of singular del Pezzo surfaces, which implies that del Pezzo surfaces of degree one whose singular points are of type $\mathbb{A}_{1}$,…

代数几何 · 数学 2012-10-04 Ivan Cheltsov , Dimitra Kosta

T.Kishimoto raised the problem to classify all compactifications of contractible affine 3-folds into smooth Fano 3-folds with second Betti number two and classified such compactifications whose log canonical divisors are not nef. In this…

代数几何 · 数学 2017-08-10 Masaru Nagaoka

Welschinger invariants are signed counts of real rational curves satisfying contraints. Quadratic Gromov--Witten invariants give such counts over general fields of characteristic different from 2 and 3. For rational del Pezzo surfaces over…

代数几何 · 数学 2025-09-05 Erwan Brugallé , Johannes Rau , Kirsten Wickelgren

Let (X,D) be a dlt pair, where X is a normal projective variety. Let S denote the support of the rounddown of D, and K the canonical divisor of X. We show that any smooth family of canonically polarized varieties over X\S is isotrivial if…

代数几何 · 数学 2019-02-20 Daniel Lohmann

In dimension two, we reduce the classification problem for asymptotically log Fano pairs to the problem of determining generality conditions on certain blow-ups. In any dimension, we prove the rationality of the body of ample angles of an…

代数几何 · 数学 2024-11-20 Paolo Cascini , Jesus Martinez-Garcia , Yanir A. Rubinstein

We develop a general approach to prove K-stability of Fano varieties. The new theory is used to (a) prove the existence of K\"ahler-Einstein metrics on all smooth Fano hypersurfaces of Fano index two, (b) to compute the stability thresholds…

代数几何 · 数学 2022-06-15 Hamid Abban , Ziquan Zhuang

The global log canonical threshold of each non-singular complex del Pezzo surface was computed by Cheltsov. The proof used Koll\'ar-Shokurov's connectedness principle and other results relying on vanishing theorems of Kodaira type, not…

代数几何 · 数学 2016-07-12 Jesus Martinez-Garcia

The Okounkov body is a construction which, to an effective divisor D on an n-dimensional algebraic variety X, associates a convex body in the n-dimensional Euclidean space R^n. It may be seen as a generalization of the moment polytope of an…

代数几何 · 数学 2016-03-04 Shin-Yao Jow

By Jahnke-Peternell-Radloff and Takeuchi, almost Fano threefolds with del Pezzo fibrations were classified. Among them, there exists 10 classes such that the existence of members of these was not proved. In this paper, we construct such…

代数几何 · 数学 2016-03-24 Takeru Fukuoka

We study (smooth, complex) Fano 4-folds X with Picard number rho(X)>6. We show that if rho(X)>9, then X is a product of del Pezzo surfaces, thus improving recent results by the author and by the author and S.A. Secci; the statement is now…

代数几何 · 数学 2025-09-01 C. Casagrande

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…

代数几何 · 数学 2007-06-18 Ivan Cheltsov

We provide new examples of K-unstable polarized smooth del Pezzo surfaces using a flopped version first used by Cheltsov and Rubinstein of the test configurations introduced by Ross and Thomas. As an application, we provide new obstructions…

代数几何 · 数学 2020-10-02 Ivan Cheltsov , Jesus Martinez-Garcia

In this paper, we investigate K-polystability on smooth complex Fano 4-folds with Lefschetz defect at least 2, focusing on the case of Lefschetz defect 3 and on Casagrande-Druel Fano 4-folds with Lefschetz defect 2. We show that exactly 5…

代数几何 · 数学 2025-12-16 Eleonora A. Romano , Saverio A. Secci