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In this paper we introduce a notion of rational singularities associated to pairs $(X, \ba^t)$ where $X$ is a variety, $\ba$ is an ideal sheaf and $t$ is a nonnegative real number. We prove that most standard results about rational…

Algebraic Geometry · Mathematics 2009-04-28 Karl Schwede , Shunsuke Takagi

Higher rational and higher Du Bois singularities have recently been introduced as natural generalizations of the standard definitions of rational and Du Bois singularities. In this note, we discuss these properties for isolated…

Algebraic Geometry · Mathematics 2025-09-10 Robert Friedman , Radu Laza

We prove that the minimal exponent for local complete intersections satisfies an Inversion-of-Adjunction property. As a result, we also obtain the Inversion of Adjunction for higher Du Bois and higher rational singularities for local…

Algebraic Geometry · Mathematics 2025-05-28 Qianyu Chen

We prove inversion of adjunction for higher rational singularities.

Algebraic Geometry · Mathematics 2026-05-06 Tatsuro Kawakami , Jakub Witaszek

We extend the notions of higher Du Bois and higher rational singularities to pairs in the sense of the minimal model program. We extend numerous results to these higher pairs, including Bertini type theorems, stability under finite maps and…

Algebraic Geometry · Mathematics 2026-03-12 Haoming Ning , Brian Nugent

Let $X$ be a variety and $H$ a Cartier divisor on $X$. We prove that if $H$ has Du Bois (or DB) singularities, then $X$ has Du Bois singularities near $H$. As a consequence, if $X \to S$ is a family over a smooth curve $S$ whose special…

Algebraic Geometry · Mathematics 2012-07-05 Sándor J Kovács , Karl Schwede

We study the behavior of Du~Bois singularities under base change and fiber products. For embeddable varieties in characteristic zero, we show that Du~Bois singularities descend from any field extension. We also prove that the product of a…

Algebraic Geometry · Mathematics 2025-12-19 Pat Lank

We prove that the higher direct images $R^qf_*\Omega^p_{\mathcal Y/S}$ of the sheaves of relative K\"ahler differentials are locally free and compatible with arbitrary base change for flat proper families whose fibers have $k$-Du Bois local…

Algebraic Geometry · Mathematics 2025-09-10 Robert Friedman , Radu Laza

Rational pairs, recently introduced by Koll\'ar and Kov\'acs, generalize rational singularities to pairs $(X,D)$. Here $X$ is a normal variety and $D$ is a reduced divisor on $X$. Integral to the definition of a rational pair is the notion…

Algebraic Geometry · Mathematics 2014-11-18 Lindsay Erickson

We generalize the notions of F-regular and F-pure rings to pairs $(R,\a^t)$ of rings $R$ and ideals $\a \subset R$ with real exponent $t > 0$, and investigate these properties. These ``F-singularities of pairs'' correspond to singularities…

Algebraic Geometry · Mathematics 2009-11-10 Shunsuke Takagi

We prove the existence of a family $\mathcal{X}\rightarrow B$ of smooth projective fourfolds, such that the very general fiber $\mathcal{X}_t$ is not stably rational (a fortiori not rational), but some special fibers $\mathcal{X}_t$ are…

Algebraic Geometry · Mathematics 2015-12-23 Claire Voisin

We introduce new notions of $k$-Du Bois and $k$-rational singularities, extending the previous definitions in the case of local complete intersections (lci), to include natural examples outside of this setting. We study the stability of…

Algebraic Geometry · Mathematics 2023-11-15 Wanchun Shen , Sridhar Venkatesh , Anh Duc Vo

We establish a characterization of the Du Bois complex of a reduced pair $(X,Z)$ when $X\smallsetminus Z$ has rational singularities. As an application, when $X$ has normal Du Bois singularities and $Z$ is the locus of non-rational…

Algebraic Geometry · Mathematics 2024-02-09 Sung Gi Park

We prove the following theorem characterizing Du Bois singularities. Suppose that $Y$ is smooth and that $X$ is a reduced closed subscheme. Let $\pi : \tld Y \to Y$ be a log resolution of $X$ in $Y$ that is an isomorphism outside of $X$. If…

Algebraic Geometry · Mathematics 2009-03-25 Karl Schwede

A partial answer is given to a question raised by Kov\'acs and Taji in arxiv:2307.07192, namely that the relative Du Bois complex of a family parametrized by a non-singular curve commutes with base change to a general point on the base. It…

Algebraic Geometry · Mathematics 2025-08-06 Caleb Ji , Sándor Kovács

We investigate properties of potentially Du Bois singularities, that is, those that occur on the underlying space of a Du Bois pair. We show that a normal variety $X$ with potentially Du Bois singularities and Cartier canonical divisor…

Algebraic Geometry · Mathematics 2020-11-10 Patrick Graf , Sándor J Kovács

Rational pairs generalize the notion of rational singularities to reduced pairs $(X,D)$. In this paper we deal with the problem of determining whether a normal variety $X$ has a rationalizing divisor, i.e. a reduced divisor $D$ such that…

Algebraic Geometry · Mathematics 2015-11-16 Lorenzo Prelli

We prove the precise inversion of adjunction formula for quotient singularities. As an application, we prove the semi-continuity of minimal log discrepancies for hyperquotient singularities. This paper is a continuation of arXiv:2011.07300,…

Algebraic Geometry · Mathematics 2024-08-19 Yusuke Nakamura , Kohsuke Shibata

We prove a precise inversion of adjunction formula for the log pair associated to a non-degenerate hypersurface. As a corollary, the minimal log discrepancies of non-degenerate normal hypersurface singularities are bounded from above by…

Algebraic Geometry · Mathematics 2007-05-23 Florin Ambro

This work establishes simple criteria for detecting higher rational singularities via the intersection Du Bois complex and the irrationality complex of a normal variety over the complex numbers.

Algebraic Geometry · Mathematics 2025-07-22 Sándor Kovács , Pat Lank , Sridhar Venkatesh
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