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We survey what is known about Fano threefold weighted complete intersections from the point of view of birational rigidity.

Algebraic Geometry · Mathematics 2025-08-20 Tiago Duarte Guerreiro , Takuzo Okada

Solutions to scalar curvature equations have the property that all possible blow-up points are isolated, at least in low dimensions. This property is commonly used as the first step in the proofs of compactness. We show that this result…

Analysis of PDEs · Mathematics 2014-03-11 Frédéric Robert , Jérôme Vétois

We answer a question raised by Caucher Birkar for singularities of weighted blowups of $\mathbb{A}^n$, if $n\leq 3$.

Algebraic Geometry · Mathematics 2019-12-13 Yifei Chen

Sextic double solids, double covers of $\mathbb P^3$ branched along a sextic surface, are the lowest degree Gorenstein Fano 3-folds, hence are expected to behave very rigidly in terms of birational geometry. Smooth sextic double solids, and…

Algebraic Geometry · Mathematics 2024-12-25 Erik Paemurru

Extending previous results, we prove that for $n \ge 5$ all hypersurfaces of degree $n+1$ in ${\mathbb P}^{n+1}$ with isolated ordinary double points are birational superrigid and K-stable, hence admit a weak K\"ahler--Einstein metric.

Algebraic Geometry · Mathematics 2022-01-19 Tommaso de Fernex

We study 4D N=2 superconformal theories that arise from the compactification of 6D N=(2,0) theories of type A_{2N-1} on a Riemann surface C, in the presence of punctures twisted by a Z_2 outer automorphism. We describe how to do a complete…

High Energy Physics - Theory · Physics 2012-12-18 Oscar Chacaltana , Jacques Distler , Yuji Tachikawa

In this work, we consider the singular set in the thin obstacle problem with weight $|x_{n+1}|^a$ for $a\in (-1, 1)$, which arises as the local extension of the obstacle problem for the fractional Laplacian (a non-local problem). We develop…

Analysis of PDEs · Mathematics 2021-08-25 Xavier Fernández-Real , Yash Jhaveri

Fold singular points play important roles in the theory of maximal surfaces. For example, if a maximal surface admits fold singular points, it can be extended to a timelike minimal surface analytically. Moreover, there is a duality between…

Differential Geometry · Mathematics 2016-02-24 Atsufumi Honda , Miyuki Koiso , Kentaro Saji

This four-pages note is an invitation to explore explicit K-stability for arbitrary K\"ahler classes of low dimension and low rank spherical varieties. We apply our simple combinatorial criterion of K-stability of rank one spherical…

Algebraic Geometry · Mathematics 2024-08-26 Thibaut Delcroix

We give a complete proof of the so called $8n^2$-inequality, a local inequality for the self-intersection of a movable linear system at an isolated centre of a non canonical singularity. The inequality was suggested and several times…

Algebraic Geometry · Mathematics 2008-11-04 Aleksandr Pukhlikov

We classify three dimensional isolated weighted homogeneous rational complete intersection singularities, which define many new four dimensional N=2 superconformal field theories. We also determine the mini-versal deformation of these…

High Energy Physics - Theory · Physics 2016-04-28 Bingyi Chen , Dan Xie , Shing-Tung Yau , Stephen S. -T. Yau , Huaiqing Zuo

Let $X$ be a cubic fourfold that has only simple singularities and does not contain a plane. We prove that the Fano variety of lines on $X$ has the same analytic type of singularity as the Hilbert scheme of two points on a surface with only…

Algebraic Geometry · Mathematics 2018-04-03 Ryo Yamagishi

We consider the problem of existence of constant scalar curvature Kaehler metrics on complete intersections of sections of vector bundles. In particular we give general formulas relating the Futaki invariant of such a manifold to the weight…

Algebraic Geometry · Mathematics 2019-09-12 Claudio Arezzo , Alberto Della Vedova

We show that five of Reid's Fano 3-fold hyperurfaces containing at least one compound Du Val singularity of type $cA_n$ have pliability at least two. The two elements of the pliability set are the singular hypersurface itself, and another…

Algebraic Geometry · Mathematics 2023-01-10 Livia Campo

In this paper, we investigate the local boundedness of weak solutions to degenerate parabolic double phase equation of type $$ u_t-\textrm{div}(|Du|^{p-2}Du+a(x,t)|Du|^{q-2}Du)=0\quad \text{in } \Omega_T := \Omega\times (0,T), $$ where…

Analysis of PDEs · Mathematics 2026-04-17 Bogi Kim , Jehan Oh

In this paper, we study the Miyaoka type inequality on Chern classes of terminal projective $3$-folds with nef anti-canonical divisors. Let $X$ be a terminal projective $3$-fold such that $-K_X$ is nef. We show that if $c_1(X)\cdot…

Algebraic Geometry · Mathematics 2025-01-17 Masataka Iwai , Chen Jiang , Haidong Liu

We describe local mirror symmetry from a mathematical point of view and make several A-model calculations using the mirror principle (localization). Our results agree with B-model computations from solutions of Picard-Fuchs differential…

High Energy Physics - Theory · Physics 2009-09-25 T. -M. Chiang , A. Klemm , S. -T. Yau , E. Zaslow

In this paper we show that a general element of $|-K_X|$ on a four-dimensional Fano manifold has at most terminal singularities. We then determine an explicit local expression of these singular points.

Algebraic Geometry · Mathematics 2015-05-12 Liana Heuberger

We complete the analysis on the birational rigidity of quasismooth Fano 3-fold deformation families appearing in the Graded Ring Database as a complete intersection. When such a deformation family $X$ has Fano index at least 2 and is…

Algebraic Geometry · Mathematics 2023-01-18 Tiago Duarte Guerreiro

We introduce a variant of the Seiberg-Witten equations, Pin^-(2)-monopole equations, and give its applications to intersection forms with local coefficients of 4-manifolds. The first application is an analogue of Froyshov's results on…

Geometric Topology · Mathematics 2013-11-08 Nobuhiro Nakamura