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A smooth, projective surface $S$ is called a $\emph{standard isotrivial fibration}$ if there exists a finite group $G$ which acts faithfully on two smooth projective curves $C$ and $F$ so that $S$ is isomorphic to the minimal…

Algebraic Geometry · Mathematics 2014-05-19 Ernesto Mistretta , Francesco Polizzi

We give a new construction of the irregular, generalized Lagrangian, surfaces of general type with p_g=5, \chi=2, K^2=8, recently discovered by Chad Schoen. Our approach proves that, if S is a general Schoen surface, its canonical map is a…

Algebraic Geometry · Mathematics 2013-03-08 Ciro Ciliberto , Margarida Mendes Lopes , Xavier Roulleau

It is proved that if $S\subset \mathbb P^N$ is a smooth projective surface and $f:S\to \mathbb P^2$ is a generic linear projection branched over a cuspidal curve $B\subset \mathbb P^2$, then the surface $S$ is determined uniquely up to an…

Algebraic Geometry · Mathematics 2007-05-23 Vik. S. Kulikov

We classify normal stable surfaces with $K_X^2 = 1$, $p_g = 2$ and $q=0$ with a unique singular point which is a non-canonical T-singularity, thus exhibiting two divisors in the main component and a new irreducible component of the moduli…

Algebraic Geometry · Mathematics 2020-12-11 Marco Franciosi , Rita Pardini , Julie Rana , Sönke Rollenske

We construct a surface with irregularity $q=2,$ geometric genus $p_g=3,$ self-intersection of the canonical divisor $K^2=16$ and canonical map of degree $16.$

Algebraic Geometry · Mathematics 2015-06-22 Carlos Rito

We describe, for various degenerations $S\to \Delta$ of quartic $K3$ surfaces over the complex unit disk (e.g., to the union of four general planes, and to a general Kummer surface), the limits as $t\in \Delta^*$ tends to 0 of the Severi…

Algebraic Geometry · Mathematics 2014-06-03 Ciro Ciliberto , Thomas Dedieu

Let $S$ be a {\em Todorov surface}, {\it i.e.}, a minimal smooth surface of general type with $q=0$ and $p_g=1$ having an involution $i$ such that $S/i$ is birational to a $K3$ surface and such that the bicanonical map of $S$ is composed…

Algebraic Geometry · Mathematics 2008-04-15 Carlos Rito

Let $S$ be a minimal smooth projective surface of general type with irregularity $q=2$. We show that, if $S$ has a nontrivial holomorphic automorphism acting trivially on the cohomology with rational coefficients, then it is a surface…

Algebraic Geometry · Mathematics 2017-12-07 Wenfei Liu

We give a survey of our previous work on relatively minimal isotrivial fibrations $\alpha \colon X \to C$, where $X$ is a smooth, projective surface and $C$ is a curve. In particular, we consider two inequalities involving the numerical…

Algebraic Geometry · Mathematics 2023-05-03 Francesco Polizzi

We relate the existence of some surfaces of general type and maximal Albanese dimension to the existence of some monodromy representations of the braid group $\mathsf{B}_2(C_2)$ in the symmetric group $\mathsf{S}_n$. Furthermore, we compute…

Algebraic Geometry · Mathematics 2018-04-09 Francesco Polizzi

Let $X$ be a smooth compact complex surface subject to the following conditions: (i) the canonical line bundle $\mathcal{O}_X(K_X) $ is very ample, (ii) the irregularity $q(X): = h^1(\mathcal{O}_X) =0$, (iii) $X$ contains no rational normal…

Algebraic Geometry · Mathematics 2018-03-06 Igor Reider

In this paper we show that locally there exists a Willmore deformation between minimal surfaces in $S^{n+2}$ and minimal surfaces in $H^{n+2}$, i.e., there exists a smooth family of Willmore surfaces $\{y_t,t\in[0,1]\}$ such that…

Differential Geometry · Mathematics 2020-11-03 Changping Wang , Peng Wang

Severi varieties and Brill-Noether theory of curves on K3 surfaces are well understood. Yet, quite little is known for curves on abelian surfaces. Given a general abelian surface $S$ with polarization $L$ of type $(1,n)$, we prove…

Algebraic Geometry · Mathematics 2015-03-25 Andreas Leopold Knutsen , Margherita Lelli-Chiesa , Giovanni Mongardi

A compact complex manifold X is said to be rationally cohomologically rigidified if its automorphism group Aut(X) acts faithfully on the cohomology ring H*(X,Q). In this note, we prove that, surfaces of general type with irregularity q>2…

Algebraic Geometry · Mathematics 2012-10-03 Jin-Xing Cai , Wenfei Liu , Lei Zhang

We construct a surface with log terminal singularities and ample canonical class that has $K_X^2=1/48 983$ and a log canonical pair $(X,B)$ with a nonempty reduced divisor $B$ and ample $K_X+B$ that has $(K_X+B)^2 = 1/462$. Both examples…

Algebraic Geometry · Mathematics 2017-02-01 Valery Alexeev , Wenfei Liu

We give an explicit construction of any simply-connected superconformal surface $\phi\colon M^2\to \R^4$ in Euclidean space in terms of a pair of conjugate minimal surfaces $g,h\colon M^2\to\R^4$. That $\phi$ is superconformal means that…

Differential Geometry · Mathematics 2007-10-30 Marcos Dajczer , Ruy Tojeiro

We study almost complex surfaces in the nearly K\"ahler $S^3\times S^3$. We show that there is a local correspondence between almost complex surfaces and solutions of the H-surface equation introduced by Wente. We find a global holomorphic…

Differential Geometry · Mathematics 2014-01-13 John Bolton , Bart Dioos , Luc Vrancken

Let $K$ be an imaginary quadratic field. Modular forms for GL(2) over $K$ are known as Bianchi modular forms. Standard modularity conjectures assert that every weight 2 rational Bianchi newform has either an associated elliptic curve over…

Number Theory · Mathematics 2019-01-16 Ciaran Schembri

Let $S$ be a minimal surface of general type with $p_g(S)=2$ and $K^2_S=1$, so called by a minimal $(1,2)$-surface. Then we obtain that the global log canonical threshold of the surface $S$ via $K_S$ is greater than equal to $\frac{1}{2}$.…

Algebraic Geometry · Mathematics 2018-05-07 In-Kyun Kim , YongJoo Shin , Joonyeong Won

In this note it is shown that, given a smooth minimal complex surface of general type S with p_g(S)=0, K^2_S=3, for which the bicanonical map is a morphism, then the degree of the bicanonical map of S is not equal to 3. This completes our…

Algebraic Geometry · Mathematics 2007-05-23 Margarida Mendes Lopes , Rita Pardini
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