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A compact complex surface with positive definite intersection lattice is either the projective plane or a false projective plane. If the intersection lattice is negative definite, the surface is either a non-minimal secondary Kodaira…

Algebraic Geometry · Mathematics 2021-01-13 Chris Peters

We show that any finite triangulation of the real projective plane or the dunce hat is partitionable. To prove this, we introduce simple yet useful gluing tools that allow us to reduce partitionability of a given complex to that of smaller…

Combinatorics · Mathematics 2022-07-19 Andrés D. Santamaría-Galvis

A recent paper showed how to find sets of finite affine or projective planes constructed on a common set of points, so that lines of one plane meet lines of a different plane in at most two points. In this paper, those results are…

Combinatorics · Mathematics 2024-03-20 Mark Saaltink

In this article, the projectivity of finitely generated flat modules of a commutative ring are studied from a topological point of view. Then various interesting results are obtained. For instance, it is shown that if a ring has either a…

Commutative Algebra · Mathematics 2019-01-23 Abolfazl Tarizadeh

We prove that any smooth rational projective surface over the field of complex numbers has an open covering consisting of 3 subsets isomorphic to affine planes.

Algebraic Geometry · Mathematics 2022-03-23 Jorge Caravantes , J. Rafael Sendra , David Sevilla , Carlos Villarino

A family of plane oriented continuous paths depending on a fixed real positive number $R$ is considered. For any point $x$ on the path, the previous points lie out of any circle of radius $R$ having at $x$ interior normal in a suitable…

Dynamical Systems · Mathematics 2020-04-13 Nico Lombardi , Marco Longinetti , Paolo Manselli , Adriana Venturi

A fake projective plane is a smooth complex surface which is not the complex projective plane but has the same Betti numbers as the complex projective plane. The first example of such a surface was constructed by David Mumford in 1979 using…

Algebraic Geometry · Mathematics 2019-03-07 Gopal Prasad , Sai-Kee Yeung

A finite linear space is a finite set of points and lines, where any two points lie on a unique line. Well known examples include projective planes. This project focuses on linear spaces which admit certain types of symmetries. Symmetries…

Combinatorics · Mathematics 2007-05-23 Gregory Cresp

We observe that Hall's free projective extension $P \mapsto F(P)$ of partial planes is a Borel map, and use a modification of the construction introduced in [9] to conclude that the class of countable non-Desarguesian projective planes is…

Logic · Mathematics 2018-11-16 Gianluca Paolini

The paper contains a general construction which produces new examples of non simply-connected smooth projective surfaces. We analyze the resulting surfaces and their fundamental groups. Many of these fundamental groups are expected to be…

alg-geom · Mathematics 2008-02-03 Fedor Bogomolov , Ludmil Katzarkov

This paper investigates flat webs on the projective plane. We present two methods for constructing such webs: the first involves taking the product of finitely many convex reduced foliations and invariant lines, while the second consists of…

Algebraic Geometry · Mathematics 2024-12-24 Carla Pracias , Maycol Falla Luza

Recently, Prasad and Yeung classified all possible fundamental groups of fake projective planes. According to their result, many fake projective planes admit a nontrivial group of automorphisms, and in that case it is isomorphic to…

Algebraic Geometry · Mathematics 2014-11-11 JongHae Keum

We propose the study of a conformally invariant functional for surfaces of complex projective plane which is closely related to the classical Willmore functional. We show that minimal surfaces of complex projective plane are critical for…

Differential Geometry · Mathematics 2007-05-23 Sebastian Montiel , Francisco Urbano

Let $p$ be a prime number, and let $k$ be an algebraically closed field of characteristic $p$. We show that the tame fundamental group of a smooth affine curve over $k$ is a projective profinite group. We prove that the fundamental group of…

Algebraic Geometry · Mathematics 2021-03-09 Hélène Esnault , Mark Shusterman , Vasudevan Srinivas

We classify projective manifolds with flat holomorphic conformal structures.

Algebraic Geometry · Mathematics 2015-03-02 Priska Jahnke , Ivo Radloff

Regular algebraic surfaces isogenous to a higher product of curves can be obtained from finite groups with ramification structures. We find unmixed ramification structures for finite groups constructed as p-quotients of particular infinite…

Group Theory · Mathematics 2011-09-29 Nathan Barker , Nigel Boston , Norbert Peyerimhoff , Alina Vdovina

Given a collection of points in the plane, classifying which subsets are collinear is a natural problem and is related to classical geometric constructions. We consider collections of points in a projective plane over a finite field such…

Algebraic Geometry · Mathematics 2023-11-29 Andrei Staicu

We show that closed, connected 4-manifolds up to connected sum with copies of the complex projective plane are classified in terms of the fundamental group, the orientation character and an extension class involving the second homotopy…

Geometric Topology · Mathematics 2023-04-13 Daniel Kasprowski , Mark Powell , Peter Teichner

The aim of this work is to describe the set of fixed point free homeomorphisms of the plane under certain expansive conditions.

Dynamical Systems · Mathematics 2009-06-26 Jorge Groisman

We prove that infinite definably simple locally finite groups of finite centraliser dimension are simple groups of Lie type over locally finite fields. Then, we identify conditions on automorphisms of a stable group that make it resemble…

Logic · Mathematics 2019-06-12 Ulla Karhumäki