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This article re-examines Lawvere's abstract, category-theoretic proof of the fixed-point theorem whose contrapositive is a `universal' diagonal argument. The main result is that the necessary axioms for both the fixed-point theorem and the…

Category Theory · Mathematics 2024-08-07 David Michael Roberts

We apply the recent results of Galkin et al. [GKMS15] to study some geometrical features of Keum's fake projective planes. Among other things, we show that the bicanonical map of Keum's fake projective planes is always an embedding.…

Algebraic Geometry · Mathematics 2017-10-25 Gennaro Di Brino , Luca F. Di Cerbo

We prove a hyperplane inequality for the surface area of projection bodies.

Metric Geometry · Mathematics 2012-04-27 Alexander Koldobsky

Stasheff showed that if a map between H-spaces is an H-map, then the suspension of the map is extendable to a map between cprojective planes of the H-spaces. Stahseff also proved the converse under the assumption that the multiplication of…

Algebraic Topology · Mathematics 2007-05-23 Yutaka Hemmi

We generalise the variant of the Babylonian tower theorem for vector bundles on projective spaces proved by I. Coanda and G. Trautmann (2006) to the case of principal $G$-bundles over projective spaces, where $G$ is a linear algebraic group…

Algebraic Geometry · Mathematics 2009-06-09 I. Biswas , I. Coanda , G. Trautmann

We prove that the integral points are potentially Zariski dense in the complement of a reduced effective singular anticanonical divisor in a smooth del Pezzo surface, with the exception of $\mathbb{P}^2$ minus three concurrent lines (for…

Algebraic Geometry · Mathematics 2023-03-23 Simone Coccia

We prove an analog of the Szemer\'edi-Trotter theorem in the plane for definable curves and points in any o-minimal structure over an arbitrary real closed field $\mathrm{R}$. One new ingredient in the proof is an extension of the well…

Logic · Mathematics 2017-07-14 Saugata Basu , Orit E. Raz

The group of piecewise projective homeomorphisms of the line provides straightforward counter-examples to the so-called von Neumann conjecture. The examples are so simple that many additional properties can be established.

Group Theory · Mathematics 2013-09-10 Nicolas Monod

Rectangular TVS-cone metric spaces are introduced and Kannan's fixed point theorem is proved in these spaces. Two approaches are followed for the proof. At first we prove the theorem by a direct method using the structure of the space…

General Topology · Mathematics 2011-02-11 Thabet Abdeljawad , Duran Türkoğlu

Ontology embedding methods are powerful approaches to represent and reason over structured knowledge in various domains. One advantage of ontology embeddings over knowledge graph embeddings is their ability to capture and impose an…

Logic in Computer Science · Computer Science 2024-10-29 Victor Lacerda , Ana Ozaki , Ricardo Guimarães

In recent years, many useful applications of the polynomial method have emerged in finite geometry. Indeed, algebraic curves, especially those defined by R\'edei-type polynomials, are powerful in studying blocking sets. In this paper, we…

Algebraic Geometry · Mathematics 2023-10-26 Shamil Asgarli , Dragos Ghioca , Chi Hoi Yip

Using results of Hironaka-Matsumura and Faltings, we prove a strong version of the well known Fulton-Hansen connectivity theorem for weighted projective spaces. As a consequence we get the following result. If $Y$ is an irreducible…

alg-geom · Mathematics 2008-02-03 Lucian Badescu

Given a projective structure on a surface $N$, we show how to canonically construct a neutral signature Einstein metric with non-zero scalar curvature as well as a symplectic form on the total space $M$ of a certain rank $2$ affine bundle…

Differential Geometry · Mathematics 2018-11-01 Maciej Dunajski , Thomas Mettler

Given a singular hypersurface in a regular 2-dimensional scheme essentially of finite type over a field, we construct an embedded resolution of singularities by weighted blow-ups. This differs from our earlier work which required…

Algebraic Geometry · Mathematics 2026-05-12 Dan Abramovich , Ming Hao Quek , Bernd Schober

Firstly we show a generalization of the (1,1)-Lefschetz theorem for projective toric orbifolds and secondly we prove that on 2k-dimensional quasi-smooth hypersurfaces coming from quasi-smooth intersection surfaces, under the Cayley trick,…

Algebraic Geometry · Mathematics 2023-02-09 William D. Montoya

Let $A$ be the one point extension of an algebra $B$ by a projective $B$-module. We prove that the extension of a given support $\tau$-tilting $B$-module is a support $\tau$-tilting $A$-module; and, conversely, the restriction of a given…

Representation Theory · Mathematics 2017-05-23 Pamela Suarez

Using toric geometry we prove a B\'ezout type theorem for weighted projective spaces.

Algebraic Geometry · Mathematics 2016-04-11 Bernt Ivar Utstøl Nødland

We completely characterize triangulations of the projective plane that have a spanning bipartite quadrangulation subgraph. This is an affirmative answer to a question by K\"undgen and Ramamurthi (J Combin Theory Ser B 85, 307--337, 2002)…

Combinatorics · Mathematics 2026-04-24 Kenta Noguchi

Using symplectic topology and the Radon transform, we prove that smooth 4-dimensional projective planes are diffeomorphic to $\mathbb{CP}^2$. We define the notion of a plane curve in a smooth projective plane, show that plane curves in high…

Differential Geometry · Mathematics 2010-09-29 Benjamin McKay

We prove an analogue in higher dimensions of the classical Narasimhan-Seshadri theorem for strongly stable vector bundles of degree 0 on a smooth projective variety $X$ with a fixed ample line bundle $\Theta$. As applications, over fields…

Algebraic Geometry · Mathematics 2014-02-26 V. Balaji , A. J. Parameswaran