Osamu Fujino
We prove that the class of log canonical rational singularities is closed under the basic operations of the minimal model program. We also give some supplementary results on the minimal model program for log canonical surfaces.
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Inversion of adjunction for higher rational singularities
本文证明了高阶有理奇点的邻接反转。
New examples of terminal and log canonical singularities
我们给出了新的例子终端和日志典型的奇点。
Equivariant Hodge modules and rational singularities
本文定义了具有有理奇点的Hodge模，并推广Boutot定理，证明了在约化群作用于仿射簇且存在稳定点时，GIT商上的诱导等变Hodge模仍保持有理奇点。
Simple surface singularities
由著名的ADE分类理性二重点是简单的。有理三重点也很简单。我们猜想简单法曲面奇点就是有理奇点，其分解图可以由有理二重点或有理三重点的图通过使（某些）顶点权值更负得到.对于有理奇点，我们通常展示一个方向，而在有理四重点和夹层奇点的特殊类别中展示另一个方向（简单性）。
Cotangent cohomology of rational surface singularities
我们证明了对于所有有理曲面奇点Y，n阶余切上同调群（n >=2）的生成元个数是相同的.对于一大类有理曲面奇点，包括商奇点，这个数也是维数。对于它们，我们得到了相应的Poincare级数的一个显式公式。
On the classification of rational surface singularities
给出了有理曲面奇点图分类的一般策略。对于每一个最大的合理二重点配置，我们调查的基本循环中可能的多重性。我们对某些类型的图进行完全分类。这允许将有理奇点的分类扩展到多重性8。我们还讨论了有理分解图的复杂性。
We prove that the Hilbert scheme of points on a normal quasi-projective surface with at worst rational double point singularities is irreducible.
We classify some special classes of non-rational Fano threefolds with terminal singularities. In particular, all such hyperelliptic and trigonal varieties are found.
On Fano threefolds with canonical Gorenstein singularities
我们分类的三维Fano品种与典型的Gorenstein奇点的程度大于64。
Singularities of Rational Curves on K3 surfaces
证明了一般K3曲面的任一亏格的本原类中的每一条有理曲线都是结点曲线。
We show that any union of slc strata of a Fano log pair with semi-log canonical singularities is simply connected. In particular, Fano log pairs with semi-log canonical singularities are simply connected, which confirms a conjecture of the first author.
Classification of three-dimensional exceptional log canonical hypersurface singularities II
本文给出了不满足良构性条件的三维例外正则超曲面奇点的详细分类。这个结果完成了在[4]（math.AG 0201025）中开始的三维例外对数正则超曲面奇点的分类。
In this paper, we classify del Pezzo foliations on projective manifolds of rank at least 3 and with log canonical singularities in the sense of McQuillan.
We provide a complete classification of Fano threefolds X having canonical Gorenstein singularities and the anticanonical degree (-KX)^3 equal 64.
On the cotangent cohomology of rational surface singularities with almost reduced fundamental cycle
通过计算余切空间$T^{1}$和$T^{2}$的一般维数公式中的修正项，证明了一类有理曲面奇点的余切空间的维数公式.我们得到了有理曲面奇点$X$的对偶图不包含特定类型的构形时，修正项为零，这推广了Theo de Jong关于有理行列式曲面奇点的修正项$c(X)$为零的一个结果.特别地，我们的结果意味着$c(X)$是零的Riemenschneiders拟行列式有理曲面奇性，这也推广了结果的qoutient奇性。
Nonisolated forms of rational triple point singularities of surfaces and their resolutions
本文详细研究了多重有理奇点（简称RTP奇点）。本文给出了一类非孤立的超曲面奇点，它们的正规化是它们的RTP-奇点，并通过对它们的Newton多边形的剖分构造了它们的极小分解图。孤立的完全相交奇点。我们证明了RTP奇点的非孤立形式及其正规化都是牛顿非退化的。
A remark on Fano threefolds with canonical Gorenstein singularities
我们给出了具有典型Gorenstein奇点的Fano三重的一些合理性构造。
Using the structure of the jet schemes of rational double point singularities, we construct "minimal embedded toric resolutions" of these singularities. We also establish, for these singularities, a correspondence between a natural class of irreducible components of the jet schemes centered at the singular locus and the set of divisors which appear on every "minimal embedded toric resolution". We prove that this correspondence is bijective except for the $E_8$ singulartiy. This can be thought as an embedded Nash correspondence for rational double point singularities.
Log canonical thresholds of quasi-ordinary hypersurface singularities
不可约的准普通超曲面奇点的对数正则阈值计算，使用一个明确的列表的motivic zeta函数的候选人发现的最后两位作者。
Rational singularities
本文提出有理奇点的无消解定义，证明其与通常定义等价，并建立新的Kempf型判别准则，进而证明Cohen-Macaulay dlt奇点在任意特征下均为有理奇点。
The purpose of this note is to show that in characteristic two there exists a smooth Fano variety for which the square of the anti-canonical bundle violates Kodaira vanishing. This is used in turn to construct non-Cohen-Macaulay canonical singularities in characteristic two.
Rational singularities and $q$-birational morphism
本文推广了任意秩为1的反射层的奇点概念，将其与[Kov11]中的有理奇点联系起来，并证明了有理奇点标准事实的推广；通过定义非有理点集，引入$(B_{q+1})$作为Serre的$(S_{q+1})$的对偶概念，并证明了关于$q$-双有理态射的定理。
Hodge-Witt cohomology and Witt-rational singularities
我们证明了在完满域上的正常有限同分向量之间的纯不可分的射影变换的维特向量层（和维特标准层）的高阶直像的模挠的消失。为此，我们表明，相对Hodge-Witt上同调承认一个行动的对应。作为一个应用，我们定义维特理性奇点，形成一个更广泛的类比理性奇点。特别是，有限的对偶有维特有理奇点。此外，我们还证明了一个光滑的适当格式的Witt向量上同调的挠部分是一个双有理不变量。
On weak Fano varieties with log canonical singularities
证明了具有对数正则奇点的弱Fano 3-folds的反典范除子是半充分的.此外，我们还考虑了具有对数正则奇点的弱对数Fano对的反对数典范除子的半满性。通过构造几个例子，证明了半满性一般不成立。基于这些例子，我们提出了充分条件，这似乎是最好的可能性，我们证明了在这样的条件下半满。特别地，我们得到了lc中心至多为1维的对数正则弱Fano 4-folds的反典范除子的半满性.我们还研究了具有对数正则奇点的弱对数Fano对的Kleiman-Mori锥。
We give a classification of the dual graphs of the exceptional divisors on the minimal resolutions of log canonical foliation singularities on surfaces. For an application, we show the set of foliated minimal log discrepancies for foliated surface triples satisfies the ascending chain condition and a Grauert-Riemenschneider type vanishing theorem for foliated surfaces with good log canonical foliation singularities.
On infinitesimal deformations and obstructions for rational surface singularities
本文的目的是证明有理曲面奇性的$T^1$和$T^2$的维数公式。这些模在解析几何和代数几何中的孤立奇点变形理论中起着重要的作用。第一个可以被认为是奇点的无穷小变形的Zapriki切空间，即它是无穷小变形的空间。第二个包含的障碍空间-在所有已知的情况下，它是整个障碍空间的理性表面奇点。
It is a conjecture of Kollár that a variety $X$ with rational singularities in some open subvariety $U$ has a rationalification; that is, a proper, birational morphism $f: Y \rightarrow X$ such that $Y$ has rational singularities, and which is an isomorphism over $U$. Whether this is true is already unknown in the case of a (normal) threefold with rational singularities along a curve $C$ except at a single point $p \in C$. There is an analogous conjecture for demi-normal varieties $X$, where we must insist that $Y$ has only semi-rational singularities. Our main result is that if a stronger ver…
The locus of log canonical singularities
LCS轨迹是Log极小模型程序的基本结果证明中的重要组成部分，如非零定理和基点自由定理。本文证明了对数标准簇的LCS轨迹具有双正规奇点。
We prove that the set of singular configurations of a general Gough Stewart platform has a rational parametrization. We introduce a reciprocal twist mapping which, for a general orientation of the platform, realizes the cubic surface of singularities as the blowing up of a quadric surface in five points.
Simple criteria for higher rational singularities
本文利用交Du Bois复形和非有理性复形，为复数域上正规簇的高次有理奇点提出了简单判别准则。
The global indices of log Calabi-Yau varieties --A supplement to Fujino's paper: The indices of log canonical singularities--
本文给出了边界上具有标准系数的logCalabi-Yau 3-folds的所有可能的整体指标，这些指标具有lc，non-klt奇点。这可以很容易地从讨论中的文件：指数的对数正则奇点的藤野（AG/9909035）。
We consider the question whether one can construct an embedded resolution of singularities of a singular variety $X\subset \textbf{A}^n$ from the data of the irreducible components of the spaces of jets (of $X$) centered at the singular locus of $X.$ We show that the answer is no in general and that it is yes for some birational models of rational triple surface singularities.
Non-rational centers of log canonical singularities
证明了如果$(X,B)$与$\dim X\geq d+2$是对数正则对，且其非klt中心的维数为$\geq d$，则$X$在每个闭点都有深度$\ge d+2$.
In this paper, we shall discuss Hilbert property of ${\rm Hilb}^{G}(\mathbb{C}^{3})$, Fujiki-Oka resolutions and iterated Fujiki-Oka resolutions for three dimensional canonical cyclic quotient singularities by using the classification shown by Ishida and Iwashita\cite{II}. Finally, we shall prove that there exists a Hilbert desingularization for any three dimensional canonical cyclic quotient singularity.
Higher F-rational singularities
本文引入更高F-理性性概念，证明在特征零域上，正常变种为m-理性当且仅当在足够大的素数p下为m-F-理性，同时建立形式的对数扩展新结果。
The higher Du Bois and higher rational properties for isolated singularities
本文研究孤立奇点的更高Du Bois与更高有理性质，在局部完全交情形下给出完整刻画，证明k-Du Bois蕴含(k-1)-有理，并建立不变量间新关系及伴随定理反转的快速证明。
Normal complex surface singularities with rational homology disk smoothings
本文证明极小好预解图至少含两个节点的正规曲面奇点无有理同伦圆盘光滑化，结合已有分类结果给出此类奇点的完整分类，同时证明了Wahl猜想及其有理猜想。
Upper bound on the multiplicity of rational and Du Bois singularities
本文证明了Du Bois奇点重数的尖锐上界，并恢复了有理奇点的已知上界，解决了Huneke和Watanabe的问题。
On the degree of Fano threefolds with canonical Gorenstein singularities
本文研究具有canonical Gorenstein奇点的Fano三维流形，证明了其度数的严格上界为72。
On Steenbrink vanishing for rational singularities in positive characteristic
本文证明正特征有理奇点的 Steenbrink 消失特殊情形，并由此推出强 F-正则三维簇及特征 p>41 的 klt 三维簇均满足 Steenbrink 消失。
The indices of log canonical singularities
设$(P\in X,Δ)$是一个三维对数正则对，使得$Δ$只有标准系数，$P$是$(X,Δ)$的对数正则奇点的中心。然后我们得到这些对的指数的有效界，并实际确定所有可能的指数。此外，在包括对数极小模型程序在内的一些假设下，还得到了$n\geq 4$维的有效界。
Given an n-dimensional variety Z with rational singularities, we conjecture that for a resolution of singularities whose reduced exceptional divisor E has simple normal crossings, the (n-1)-th higher direct image of the sheaf of differential forms with log poles along E vanishes. We prove this when Z has isolated singularities and when it is a toric variety. We deduce that for a divisor D with isolated rational singularities on a smooth complex n-dimensional variety X, the generation level of Saito's Hodge filtration on the localization of the structure sheaf along D is at most n-3.
We classify the canonical threefold singularities that allow an effective two-torus action. This extends classification results of Mori on terminal threefold singularities and of Ishida and Iwashita on toric canonical threefold singularities. Our classification relies on lattice point emptiness of certain polytopal complexes with rational vertices. Scaling the polytopes by the least common multiple $k$ of the respective denominators, we investigate $k$-emptiness of polytopes with integer vertices. We show that two dimensional $k$-empty polytopes either are sporadic or come in series given by F…
We prove that the cohomology sheaves of the relative dualizing complex of a flat family of varieties with semi-log-canonical or Du Bois singularities are flat and commute with base change. This is a local version of our earlier similar result where the family was assumed to be projective. We also derive several consequences for deformations of semi-log-canonical and of Du Bois singularities.
The Cox Ring of a Del Pezzo Surface Has Rational Singularities
对于光滑的Del Pezzo曲面，其上所有可逆层同构类的整体瓣的直和几乎可以正则地被赋予环结构，称为Cox环。我们证明了在特征0中，这个环是Gorenstein环，并且它的谱具有有理奇点。还指出了AG/0309111在数学方面的差距。
In this paper we study $(ε,δ)$-lc singularites, i.e. $ε$-lc singularities admitting a $δ$-plt blow-up. We prove that $n$-dimensional $(ε,δ)$-lc singularities are bounded up to a deformation, and $2$-dimensional $(ε,δ)$-lc singularities form a bounded family. Furthermore, we give an example which shows that $(ε,δ)$-lc singularities are not bounded in higher dimensions, even in the analytic sense.
Log-canonical forms and log canonical singularities
对于具有良好${\bf C}^*$作用的${\bf C}^n$的正规子簇$V$，当它只有对数典范奇点、对数终结奇点或有理奇点时，给出了一个简单的刻画.此外，我们能够给出的plurigenus的孤立奇点的这些品种和对数Kodaira维数的$V\backslash \{0\}$。为此，我们引入正规复空间上的$m$ -标准型和$L^{2,m}$ -标准型层。对于具有良好${\bf C}^*$作用的仿射簇的情形，我们给出了这些层的对偶层的分次及其张量幂幂的显式公式。
The Bogomolov-Gieseker-Koseki inequality on surfaces with canonical singularities in arbitrary characteristic
本文将Bogomolov-Gieseker不等式从特征零光滑射影曲面推广到任意特征、具典范奇点的射影曲面，并推广其若干经典应用。
On the degree of Fano threefolds with canonical Gorenstein singularities, I
我们考虑具有正则Gorenstein奇点的Fano三重$X$。在进一步假设$X$至少有一个非cDV点的条件下，我们证明了其度的一个精确界：$-K_X^3\le 72$ .
Blow-ups of canonical singularities
本文应用Shokurov的归纳法研究了终端奇点和正则奇点。作为一个简单的后果的极小模型计划，我们表明，任何三维日志终端奇点存在一些特殊的，所谓的，plt爆破。我们讨论了它们的性质，并构造了一些例子。
Examples of Hirzebruch-Milnor classes of projective hypersurfaces detecting higher du Bois or rational singularities
本文表明经典 Hirzebruch-Milnor 类仅在特殊情形下能检测射影超曲面的更高 du Bois 或有理奇点，并澄清了作者早期论文中的若干要点。
Higher Du Bois and higher rational singularities of hypersurfaces
本研究针对全局定义的超曲面，利用消失循环混合霍奇模的Hodge滤过给出高阶Du Bois与高阶有理奇点的等价刻画，并提出基于谱Hirzebruch-Milnor特征类的同调检测准则。
Rational curves on Fano threefolds with Gorenstein terminal singularities
本文研究具有Gorenstein终端奇点的Fano三维簇上的有理曲线，推广了几何Manin猜想至奇异情形，并证明了某些奇异del Pezzo三维簇的该猜想。
Classification of rational unicuspidal projective curves whose singularities have one Puiseux pair
刻画d次射影平面曲线C的局部平面曲线奇点的嵌入拓扑型的集合是一个非常古老而有趣的公开问题。本文的目的是给出一个完整的（拓扑）分类的情况下，C是合理的，它有一个独特的奇点，这是局部不可约（即C是单尖）与一个Pui-pix对。
The $\ell$-adic Dualizing Complex on an Excellent Surface with Rational Singularities
在这篇文章中，我们表明，如果$X$是一个优良的曲面与合理的奇性，常数层$\mathbb{Q}_{\ell}$是一个对偶复合物。在系数$\mathbb{Z}_{\ell}$中，我们还证明了$\mathbb{Z}_{\ell}$成为对偶复形的障碍在于奇点处的除子类群。作为应用，我们研究了这类曲面上的$\ell$ -adic上同调群的反常层和权。
Elliptic Gorenstein singularities, log canonical thresholds and log Enriques surfaces
我们指出了超曲面椭圆奇点和log Enriques曲面之间的一个有趣的关系：除了少数例外，每个超曲面椭圆奇点定义了一些klt log Enriques曲面$(S,Diff)$。在许多情况下，$(S,Diff)$的对数典范覆盖是一个具有“大”非辛自同构群的Du Val K3曲面。
Boundedness of total Cartier indices for rational singularities in families
本文研究了有理奇点族中变种的总Cartier指数有界性问题，通过分别处理二维和高维情况，解决了Han和Jiang提出的问题。
We show that the minimal log discrepancy of any $\mathbb Q$-Gorenstein non-canonical threefold is $\leq\frac{12}{13}$, which is an optimal bound.
Rational singularities of normal T-varieties
T-簇是具有代数环面T的有效正则作用的代数簇X。Altmann和Hausen利用多面体因子给出了仿射T-簇X的组合描述。在本文中，我们计算的高直接图像的结构层的去奇异化的X在此组合数据。作为结果，我们给出了一个标准，当一个T-簇有合理的奇异性。我们还提供了T-簇是Cohen-Macaulay簇的一个部分判据。作为应用，我们在这方面的特点拟齐次椭圆奇异曲面。
The weighted dual graph of a two-dimensional normal singularity $(X, x)$ represents the topological nature of the exceptional locus of its minimal log resolution. $(X, x)$ and its graph are said to be taut if the singularity can be uniquely determined by the graph. Laufer gave a complete list of taut singularities over $\mathbb{C}$. In positive characteristics, taut graphs over $\mathbb{C}$ are not necessarily taut and tautness have been studied only for special cases. In this paper, we prove the tautness of $F$-regular singularities. We also discuss the tautness of $F$-pure rational singulari…
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