Skip to main content

All Questions

Filter by
Sorted by
Tagged with
4 votes
1 answer
175 views

Every elliptic surface contains only finitely many negative self-intersection rational curves?

By a properly elliptic surface, I mean an algebraic surface $X$ with Kodaira dimension $\kappa(X)=1$. It has a natural elliptic fibration $\pi\colon X\rightarrow S$. According to section 5.2 of this ...
notime's user avatar
  • 141
2 votes
0 answers
95 views

Reference request The support of $f$-nef divisor

I'm seaching for a proof of the theorem below. Do you know any reference? Consider $f:X\rightarrow Y$ projective birational map between normal varieties and $\mathbb{R}$ cartier divisor $D$ whose ...
George's user avatar
  • 328
1 vote
2 answers
196 views

What are the finite étale coverings of a quasi-hyperelliptic surface?

Let $X$ be a quasi-hyperelliptic surface in characteristic 3 where the canonical bundle $K_X$ is trivial. Question: Is there a finite étale covering $Y \rightarrow X$ such that $Y$ is an abelian ...
LeechLattice's user avatar
  • 9,501
4 votes
0 answers
100 views

Fundamental groups of Hirzebruch's line arrangement varities

Let $\Lambda$ be a line arrangement in $\mathbb{P}^2$ and $n > 0$ an integer. Then Hirzebruch defined a smooth projective surface $H(\Lambda, n)$ as the minimal desingularization of a covering $Y \...
Ben C's user avatar
  • 3,625
1 vote
0 answers
73 views

Explict equations for unirational Enriques surface with a nonzero 1-form

I am hoping to write down very explicitly the equations for the following data: an Enriques surface $X$ of type $\mathrm{Pic}^{\tau} = \mathbb{Z} / 2 \mathbb{Z}$ such that its canonical $\mu_2$-cover ...
Ben C's user avatar
  • 3,625
2 votes
0 answers
671 views

description of very ample bundle of Hirzebruch surface

I learned some basic properties of Hirzebruch surface mainly from Vakil's notes "the rising sea", section 20.2.9. the Hirzebruch surface is defined as $\mathbb{F}_n:=\operatorname{Proj} (\...
zxx's user avatar
  • 343
2 votes
0 answers
108 views

arithmetic del Pezzo surfaces in comparison with del Pezzo surfaces over a field

A del Pezzo surface is a smooth, 2-dimensional projective variety $X$ with ample anticanonical divisor, i.e. a 2-dimensional Fano variety. I am interested in the arithmetic analogue, a 2-dimensional ...
PrimeRibeyeDeal's user avatar
2 votes
2 answers
363 views

Why does a complex linear normalization of a real algebraic surface inherit a real structure?

Could you recommend any references to (some of) the following very basic assertions in algebraic geometry? (It seems unreasonable to reprove them in a research paper.) (1) Let a surface $X$ in $\...
Mikhail Skopenkov's user avatar
1 vote
1 answer
247 views

Infinitesimal deformation of strict transform

Let $X$ be an affine, complex surface with isolated singularities and $\pi:\widetilde{X} \to X$ be a resolution of singularities (not necessarily minimal) i.e., $\widetilde{X}$ is non-singular and $\...
Ron's user avatar
  • 2,126
2 votes
1 answer
732 views

Where to find "Families of curves on a surface of general type" (MR0457450)?

I am currently doing some research on surfaces of general type and I need some results from Bogomolov's paper: Bogomolov, F. A. Families of curves on a surface of general type. Dokl. Akad. Nauk SSSR ...
pjox's user avatar
  • 363
2 votes
1 answer
299 views

Explicit families of elliptic curves

I am interested in finding families $X\to C$ of elliptic curves over a projective curve $C$. The fibers are not all isomorphic, not all smooth, and the singular fibers should be nodal stable curves. ...
Zlatan P.'s user avatar
3 votes
1 answer
203 views

"Direct" calculation of $K_0$ for surfaces, 3-folds

I apologize in advance for the vagueness of my question, but I am looking for sources (if they exist) where $K_0$ (the Grothendieck group of coherent sheaves) is computed "by hand" for some low-...
A. S.'s user avatar
  • 528
5 votes
0 answers
326 views

Max Noether's theorem for algebraic surfaces

The well-known Max Noether's theorem for curves [see Arbarello-Cornalba-Griffiths-Harris Geometry of Algebraic Curves vol.1, p. 117] states that, if a smooth curve $C$ is non-hyperelliptic, then the ...
Francesco Polizzi's user avatar
2 votes
1 answer
714 views

Castelnuovo and Artin contractibility criteria for families

In the course of a proof, I need some version of Castelnuovo and Artin's contractibility criteria for a family of surfaces. Say I have a family (flat is probably needed, in order to compare ...
Stefano's user avatar
  • 625
6 votes
1 answer
342 views

What is Mumford's example of a normal complex algebraic surface $X$ with non-torsion elements in $H^2_{et}(X,\mathbb{G}_m)$?

I have heard that Mumford has constructed an example of a normal complex algebraic surface $X$ such that $H^2_{et}(X,\mathbb{G}_m)$ contains a non-torsion element. But I cannot find the reference. ...
Zhaoting Wei's user avatar
  • 9,019
1 vote
1 answer
493 views

Fundamental group of Log del Pezzo surfaces

A Log del Pezzo surface is a normal complex surface with ample anti-canonical bundle and at worst quotient singularities. It is known that such surfaces are rational. This is proven, for example, ...
aglearner's user avatar
  • 14.3k
3 votes
1 answer
414 views

Modern reference for the theory of correspondences for curves

The classic theory of correspondences between smooth algebraic curves can be found in André Weil's Foundations of algebraic geometry. However, this reference works in a pre-modern algebraic geometry ...
Tintin's user avatar
  • 2,871
3 votes
3 answers
515 views

Does there exist a holomorphic fibration of genus two over $\mathbb{P}^{1}$ with $7$ nodal singularities?

This is a problem about the holomorphic fibration on a complex manifold. Does there exist a holomorphic fibration of genus two over $\mathbb{CP}^{1}$ with 7 nodal singularities? If you are aware of ...
guest's user avatar
  • 31
3 votes
1 answer
215 views

Enriques classification of algebraic surfaces in characteristic zero

I am searching for a reference about the classification of algebraic surfaces over an arbitrary algebraically closed field of characteristic zero. In the 1949 book "le superficie algebriche" by ...
giusepe's user avatar
  • 31
10 votes
1 answer
1k views

A proper smooth surface is projective

My question is a reference request for the following fact: if $k$ is a field and $X$ a proper smooth surface over $k$, then $X \rightarrow \mathrm{Spec}\, k$ is projective. Where is this well-known ...
Lisa S.'s user avatar
  • 2,663
3 votes
1 answer
702 views

Is each rationally chain connected surface rational?

Consider a 2-dimensional smooth projective algebraic surface S over complex numbers. Could you recommend any exact references to the proofs of the following assertions (of course, if they are true): ...
Mikhail Skopenkov's user avatar
5 votes
2 answers
469 views

Reference for Automorphisms of K3 surfaces

I am looking for some introductory reference concerning Automorphisms (of finite order) on K3 surfaces. Any suggestion?
Heitor's user avatar
  • 761
2 votes
1 answer
467 views

Absorbing ramification and factoring finite flat maps

In his Algebraic surfaces book, Beauville gives a result allowing one to "absorb ramification" for certain maps (see below). There are also something similar one can do with number fields. I would ...
LMN's user avatar
  • 3,555
2 votes
1 answer
470 views

Resolution of "nice" and zero-dimensional singularities on a surface

Assume I have a singular algebraic surface $X$ over an algebraically closed field (characteristic zero if you want) which is singular in a finite set of points. I am looking for a condition as to the ...
Jesko Hüttenhain's user avatar
24 votes
3 answers
1k views

Hyperbolic Coxeter polytopes and Del-Pezzo surfaces

Added. In the following link there is a proof of the observation made in this question: http://dl.dropbox.com/u/5546138/DelpezzoCoxeter.pdf I would like to find a reference for a beautiful ...
Dmitri Panov's user avatar
  • 28.9k
13 votes
4 answers
2k views

Algebraic surfaces and their (intrinsic) geometry

Recently I began to consider algebraic surfaces, that is, the zero set of a polynomial in 3 (or more variables). My algebraic geometry background is poor, and I'm more used to differential and ...
Dror Atariah's user avatar
5 votes
1 answer
420 views

Certain double covers of cubic surfaces

Let $S$ be a smooth cubic surface in $\mathbb{P}^3$. I would like to understand that variety $V$ that parametrizes lines $\ell$ such that $\ell \cdot S=3P$ with $P \in S$. At any point $P \in S$, let $...
Siksek's user avatar
  • 3,142
7 votes
1 answer
799 views

Liftability of Enriques Surfaces (from char. p to zero)

Let $k$ be an algebraically closed field of characteristic $p > 0$, $X$ a variety over $k$. We say $X$ lifts to characteristic zero, if there exists a local ring $R$ containing $\mathbb Z$ with ...
Holger Partsch's user avatar