No Arabic abstract
We prove that the natural $(operatorname{Aff} _2(mathbf{C}),mathbf{C}^2)$-structure on an Inoue surface is the unique $(operatorname{Bir}(mathbb{P}^2),mathbb{P}^2(mathbf{C}))$-structure, generalizing a result of Bruno Klingler which asserts that the natural $(operatorname{Aff}_2(mathbf{C}),mathbf{C}^2)$-structure is the unique $(operatorname{PGL} _3(mathbf{C}),mathbb{P}^2(mathbf{C}))$-structure.
In many cases rational surfaces obtained by desingularization of birational dynamical systems are not relatively minimal. We propose a method to obtain coordinates of relatively minimal rational surfaces by using blowing down structure. We apply this method to the study of various integrable or linearizable mappings, including discre
In this paper, following Grothendieck {it Esquisse dun programme}, which was motivated by Belyis work, we study some properties of surfaces $X$ which are triangulated by (possibly ideal) isometric equilateral triangles of one of the spherical, euclidean or hyperbolic geometries. These surfaces have a natural Riemannian metric with conic singularities. In the euclidean case we analyze the closed geodesics and their lengths. Such surfaces can be given the structure of a Riemann surface which, considered as algebraic curves, are defined over $bar{mathbb{Q}}$ by a theorem of Belyi. They have been studied by many authors of course. Here we define the notion of connected sum of two Belyi functions and give some concrete examples. In the particular case when $X$ is a torus, the triangulation leads to an elliptic curve and we define the notion of a peel obtained from the triangulation (which is a metaphor of an orange peel) and relate this peel with the modulus $tau$ of the elliptic curve. Many fascinating questions arise regarding the modularity of the elliptic curve and the geometric aspects of the Taniyama-Shimura-Weil theory.
We will show that any open Riemann surface $M$ of finite genus is biholomorphic to an open set of a compact Riemann surface. Moreover, we will introduce a quotient space of forms in $M$ that determines if $M$ has finite genus and also the minimal genus where $M$ can be holomorphically embedded.
It was known to von Neumann in the 1950s that the integer lattice $mathbb{Z}^2$ forms a uniqueness set for the Bargmann-Fock space. It was later demonstrated by Seip and Wallsten that a sequence of points $Gamma$ that is uniformly close to the integer lattice is still a uniqueness set. We show in this paper that the uniqueness sets for the Fock space are preserved under much more general perturbations.
Let $X$ be a hyperbolic curve over a field $k$ finitely generated over $mathbb{Q}$. A Galois section $s$ of $pi_{1}(X)tomathrm{Gal}(bar{k}/k)$ is birational if it lifts to a section of $mathrm{Gal}(overline{k(X)}/k(X))tomathrm{Gal}(bar{k}/k)$. Grothendiecks section conjecture predicts that every Galois section of $pi_{1}(X)$ is either geometric or cuspidal, while the birational section conjecture predicts the same for birational Galois sections. Let $t$ be an indeterminate. We prove that, if $s$ is a Galois section such that the base change $s_{k(t)}$ to $k(t)$ is birational, then $s$ is geometric or cuspidal. As a consequence we prove that the section conjecture is equivalent to Esnault and Hais cuspidalization conjecture, which states that Galois sections of hyperbolic curves over fields finitely generated over $mathbb{Q}$ are birational.