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In this paper, we proved that a log smooth family of log general type klt pairs with a special (in the sense of Campana) quasi-projective base is isotrivial. As a consequence, we proved the generalized Kebekus-Kov\'acs conjecture…

Algebraic Geometry · Mathematics 2020-01-24 Chuanhao Wei , Lei Wu

We prove that a projective semistable morphism of fs log analytic spaces yields polarized log Hodge structures in the canonical way.

Algebraic Geometry · Mathematics 2023-07-11 Taro Fujisawa , Chikara Nakayama

In this paper, we prove the openness of K-semistability in families of log Fano pairs by showing that the stability threshold is a constructible function on the fibers. We also prove that any special test configuration arises from a log…

Algebraic Geometry · Mathematics 2021-11-02 Harold Blum , Yuchen Liu , Chenyang Xu

We first study hyperplane sections of some singular schemes over a field. We prove a Bertini theorem for the log smoothness of generic hyperplane sections of a large class of log smooth schemes over a log point. We also give an abstract…

Number Theory · Mathematics 2014-06-05 Rémi Lodh

In our series of papers, we prove that smooth Fano threefolds in positive characteristic lift to the ring of Witt vectors. Moreover, we show that they satisfy Akizuki-Nakano vanishing, $E_1$-degeneration of the Hodge to de Rham spectral…

Algebraic Geometry · Mathematics 2025-05-12 Tatsuro Kawakami , Hiromu Tanaka

The present paper studies the structure of characteristic varieties of fundamental groups of graph manifolds. As a consequence, a simple proof of Papadima's question is provided on the characterization of algebraic links that have…

Geometric Topology · Mathematics 2019-11-27 E. Artal Bartolo , J. I. Cogolludo-Agustín , D. Matei

We use Almgren's framework of multi-valued maps to construct a multi-valued inverse $F:f(\Omega)\to \mathcal A_d(\mathbb R^n)$ of a quasiregular map $f:\Omega\to \mathbb R^n$ of finite degree $d$. We then develop a pull-back theory of…

Differential Geometry · Mathematics 2026-01-27 Elefterios Soultanis

We prove that the cohomology jump loci in the space of rank one local systems over a smooth quasi-projective variety are finite unions of torsion translates of subtori. The main ingredients are a recent result of Dimca-Papadima, some…

Algebraic Geometry · Mathematics 2014-04-10 Nero Budur , Botong Wang

We develop a general theory of log spaces, in which one can make sense of the basic notions of logarithmic geometry, in the sense of Fontaine-Illusie-Kato. Many of our general constructions with log spaces are new, even in the algebraic…

Differential Geometry · Mathematics 2015-07-27 W. D. Gillam , Samouil Molcho

We prove that K-polystable log Fano pairs have reductive automorphism groups. In fact, we deduce this statement by establishing more general results concerning the S-completeness and $\Theta$-reductivity of the moduli of K-semistable log…

Algebraic Geometry · Mathematics 2020-12-02 Jarod Alper , Harold Blum , Daniel Halpern-Leistner , Chenyang Xu

We prove a generalization of the Fujita-Kawamata-Zuo semi-positivity Theorem for filtered regular meromorphic Higgs bundles and tame harmonic bundles. Our approach gives a new proof in the cases already considered by these authors. We give…

Algebraic Geometry · Mathematics 2017-07-27 Yohan Brunebarbe

The main aim of this article is to give new classes of smooth projective varieties over characteristic $p>0$ that admit flat liftings over the Witt vectors together with additional data (logarithmic structure and the Frobenius morphism) by…

Algebraic Geometry · Mathematics 2025-06-03 Ryo Ishizuka , Kazuma Shimomoto

By making use of Halperin's local systems over simplicial sets and the model structure of the category of diffeological spaces due to Kihara, we introduce a framework of rational homotopy theory for such smooth spaces with arbitrary…

Algebraic Topology · Mathematics 2024-06-13 Katsuhiko Kuribayashi

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

For a log Fano manifold (X, D) with D\neq 0 and with the log Fano pseudoindex \geq 2, we prove that the restriction homomorphism Pic(X)\to Pic(D_1) of Picard groups is injective for any irreducible component D_1\subset D.The strategy of our…

Algebraic Geometry · Mathematics 2012-06-13 Kento Fujita

We construct a log algebraic version of the homotopy sequence for a quasi-projective normal crossing log variety over a log point of characteristic zero and prove some exactness properties of it. Our proofs are purely algebraic.

Algebraic Geometry · Mathematics 2018-05-22 Valentina Di Proietto , Atsushi Shiho

In [Kat94b], Kato defined his notion of a log regular scheme and studied the local behavior of such schemes. A toric variety equipped with its canonical logarithmic structure is log regular. And, these schemes allow one to generalize toric…

Commutative Algebra · Mathematics 2007-05-23 Howard M Thompson

It was shown by Kaup that every origin-preserving automorphism of quasi-circular domains is a polynomial mapping. In this paper, we study how the weight of quasi-circular domains and the degree of such automorphisms are related. By using…

Complex Variables · Mathematics 2014-03-18 Atsushi Yamamori

By means of analytic methods the quasi-projectivity of the moduli space of algebraically polarized varieties with a not necessarily reduced complex structure is proven including the case of non-uniruled polarized varieties.

Algebraic Geometry · Mathematics 2007-05-23 Georg Schumacher , Hajime Tsuji

We construct a projective K-moduli space of quasimaps with a certain log Fano condition, which is regarded as a rational map from $\mathbb{P}^1$ to a projective space. Moreover, we investigate relationships between the K-moduli of quasimaps…

Algebraic Geometry · Mathematics 2026-01-09 Kenta Hashizume , Masafumi Hattori
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