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Generalizing the well-known Shafarevich hyperbolicity conjecture, it has been conjectured by Viehweg that a quasi-projective manifold that admits a generically finite morphism to the moduli stack of canonically polarized varieties is…

Algebraic Geometry · Mathematics 2007-07-16 Stefan Kebekus , Sandor J. Kovacs

A complex projective manifold is rationally connected, resp. rationally simply connected, if finite subsets are connected by a rational curve, resp. the spaces parameterizing these connecting rational curves are themselves rationally…

Algebraic Geometry · Mathematics 2017-06-20 Jason Starr , Chenyang Xu

Using the theory of moduli of curves, we establish various slope inequalities for general fibered surfaces. More precisely, we introduce the notion of functorial divisors on Artin stacks and prove a theorem concerning their effectiveness.…

Algebraic Geometry · Mathematics 2023-09-14 Makoto Enokizono

We introduce a new notion of generalized log twisted curves, which are marked nodal curves with additional data at the marked points. In the case when the markings are distinct this notion agrees with the notion of twisted curve introduced…

Algebraic Geometry · Mathematics 2025-08-13 Martin Olsson , Rachel Webb

In a previous paper [FT1], for any logarithmic symplectic pair (X,D) of a symplectic manifold X and a simple normal crossings symplectic divisor D, we introduced the notion of log pseudo-holomorphic curve and proved a compactness theorem…

Symplectic Geometry · Mathematics 2019-10-14 Mohammad Farajzadeh-Tehrani

We prove a global version of the so-called div-curl-lemma, a crucial result for compensated compactness and in homogenization theory, for mixed tangential and normal boundary conditions in bounded weak Lipschitz domains in 3D and weak…

Analysis of PDEs · Mathematics 2018-12-18 Dirk Pauly

We construct isotrivial and non-isotrivial elliptic curves over $\mathbb{F}_q(t)$ with an arbitrarily large set of separable integral points. As an application of this construction, we prove that there are isotrivial log-general type…

Number Theory · Mathematics 2012-11-06 Ricardo Conceição

We study the sheaves of logarithmic vector fields along smooth cubic curves in the projective plane, and prove a Torelli-type theorem in the sense of Dolgachev-Kapranov for those with non-vanishing j-invariants.

Algebraic Geometry · Mathematics 2007-10-11 Kazushi Ueda , Masahiko Yoshinaga

Let $(X,D)$ be a smooth log pair over $\mathbb{C}$ such that the complement $U := X \setminus D$ carries a maximally varied family of polarized manifolds. We prove a version of second main theorem on $(X,D)$ by using the Viehweg-Zuo…

Algebraic Geometry · Mathematics 2020-08-05 Ruiran Sun

We initiate the study of inflection curves of rational vector fields on the Riemann sphere. For a rational vector field $v_R=-R(z)\frac{\partial}{\partial z}, \qquad R(z)=\frac{Q(z)}{P(z)} $ we define its affine regular inflection locus by…

Dynamical Systems · Mathematics 2026-05-28 Boris Shapiro , Guillaume Tahar

Welschinger's invariant bounds from below the number of real rational curves through a given generic collection of real points in the real projective plane. We estimate this invariant using Mikhalkin's approach which deals with a…

Algebraic Geometry · Mathematics 2007-05-23 I. Itenberg , V. Kharlamov , E. Shustin

We discuss the cone theorem for quasi-log schemes and the Mori hyperbolicity. In particular, we establish that the log canonical divisor of a Mori hyperbolic projective normal pair is nef if it is nef when restricted to the non-lc locus.…

Algebraic Geometry · Mathematics 2022-12-27 Osamu Fujino

Counts of curves in $\mathbb{P}^1\times\mathbb{P}^1$ with fixed contact order with the toric boundary and satisfying point conditions can be determined with tropical methods by Mikhalkin. If we require that our curves intersect the zero-…

Algebraic Geometry · Mathematics 2022-12-22 Daniel Corey , Hannah Markwig , Dhruv Ranganathan

Given a compact oriented surface, we classify log Poisson bi-vectors whose degeneracy loci are locally modeled by a finite set of lines in the plane intersecting at a point. Further, we compute the Poisson cohomology of such structures and…

Symplectic Geometry · Mathematics 2018-09-12 Melinda Lanius

In a previous work, we gave a construction of (not necessarily realizable) oriented matroids from a triangulation of a product of two simplices. In this follow-up paper, we use a variant of Viro's patchworking to derive a topological…

Combinatorics · Mathematics 2020-10-26 Marcel Celaya , Georg Loho , Chi Ho Yuen

For a toric log variety with standard coefficients, we show that the minimal log discrepancy at a closed invariant point bounds the Cartier index of a neighbourhood.

Algebraic Geometry · Mathematics 2008-11-18 Florin Ambro

We prove that for every integer $t\geq 1$, the class of intersection graphs of curves in the plane each of which crosses a fixed curve in at least one and at most $t$ points is $\chi$-bounded. This is essentially the strongest…

Combinatorics · Mathematics 2017-10-05 Alexandre Rok , Bartosz Walczak

This is an expanded version of our work [AN88], 1988, in Russian. We classify del Pezzo surfaces over C with log terminal singularities of index \le 2. By classification, we understand a description of the intersection graph of all…

Algebraic Geometry · Mathematics 2007-05-23 Valery Alexeev , Viacheslav V. Nikulin

We prove that the moduli b-divisor of an lc-trivial fibration from a log canonical pair is log abundant. The result follows from a theorem on the restriction of the moduli b-divisor, based on a theory of lc-trivial morphisms, which allows…

Algebraic Geometry · Mathematics 2021-02-16 Zhengyu Hu

We classify graphs and, more generally, finite relational structures that are identified by C2, that is, two-variable first-order logic with counting. Using this classification, we show that it can be decided in almost linear time whether a…

Logic in Computer Science · Computer Science 2015-03-31 Sandra Kiefer , Pascal Schweitzer , Erkal Selman