DIOPHANTINE GEOMETRY on CURVES OVER FUNCTION FIELDS These Are Extended Notes of My Five Hours Lecture at the Winter School on Al
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Distribution of Rational Points on Toric Varieties: a Multi-Height Approach
Distribution of Rational Points on Toric Varieties: A Multi-Height Approach Arda H. Demirhan University of Illinois at Chicago March 19, 2021 Arda H. Demirhan Distribution of Rational Points on Toric Varieties: A Multi-Height Approach Height Machine associates counting devices to divisor classes. ( ) ( ) geometric facts arithmetic facts , given by divisor relations given by height relations Height Machine is useful for other fields too. How to Count Rational Points? X: an algebraic variety in Pn over a number field Main Idea: We use height functions to count rational points. Arda H. Demirhan Distribution of Rational Points on Toric Varieties: A Multi-Height Approach Height Machine is useful for other fields too. How to Count Rational Points? X: an algebraic variety in Pn over a number field Main Idea: We use height functions to count rational points. Height Machine associates counting devices to divisor classes. ( ) ( ) geometric facts arithmetic facts , given by divisor relations given by height relations Arda H. Demirhan Distribution of Rational Points on Toric Varieties: A Multi-Height Approach How to Count Rational Points? X: an algebraic variety in Pn over a number field Main Idea: We use height functions to count rational points. Height Machine associates counting devices to divisor classes. ( ) ( ) geometric facts arithmetic facts , given by divisor relations given by height relations Height Machine is useful for other fields too. Arda H. Demirhan Distribution of Rational Points on Toric Varieties: A Multi-Height Approach Counting Function: N(U(K); B) = cardfx 2 U(K): HK (x) ≤ Bg Let U ⊆ X be a Zariski open with some rational points. -
Arithmetic on Curves
BULLETIN (New Series) OF THE AMERICAN MATHEMATICAL SOCIETY Volume 14, Number 2, April 1986 ARITHMETIC ON CURVES BY BARRY MAZUR CONTENTS I. What are Diophantine problems? 1. Miscellaneous Diophantine problems 2. Systematic formulations 3. Digression: Questions of integral solutions vs. Questions of Diophantine approxima tions II. Curves 1. Plane curves 2. Algebraic curves 3. Smooth curves 4. Riemann surfaces 5. Simplifying the singularities of a plane curve 6. Genus 7. The fundamental trichotomy 8. Interlude: A geometric finiteness result 9. On Mordell's conjecture and its analogue III. Jacobians and abelian varieties 1. An extension of the chord-and-tangent method to curves of genus > 2: The jacobian of a curve 2. The analytic parametrization of J by algebraic integrals modulo periods 3. The algebraic nature of the jacobian 4. The arithmetic nature of the jacobian IV. Classification of families with bounded bad reduction 1. Kodaira's problem 2. Shafarevich's problems 3. Parshin's construction: Shafarevich's conjecture implies Mordell's conjecture V. Heights 1. Height of points 2. Normed vector spaces 3. Heights of abelian varieties 4. A block diagram Received by the editors June 12, 1985. 1980Mathematics Subject Classification (1985 Revision). Primary 14Hxx, 14Kxx, llDxx, 00-01, 01-01, 01A65, 11-01, 11G05, 11G10, 11G15. ©1986 American Mathematical Society 0273-0979/86 $1.00 + $.25 per page 207 License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use 208 BARRY MAZUR Bibliography 1. General references 2. References requiring some background 3. Accounts of the proof of Mordell's conjecture which require familiarity with the techniques of number theory or algebraic geometry 4. -
Heights, Algebraic Dynamics and Berkovich Analytic Spaces
HEIGHTS, ALGEBRAIC DYNAMICS AND BERKOVICH ANALYTIC SPACES JORGE PINEIRO Abstract. The present paper is an exposition on heights and their importance in the modern study of algebraic dynamics. We will explain the idea of canonical height and its surprising relation to algebraic dynamics, invariant measures, arithmetic intersection theory, equidistribution and p-adic analytic geometry. 1. Introduction In many situations, solving mathematical problems involves study the solution set of a system of polynomial equations. The language of algebraic varieties is developed for that purpose. An algebraic variety is a topological locally ringed space whose underlying topological space \behave locally like" the zero set of a system of polynomials in an a±ne space. A formal de¯nition can be found for example in Chapter 1 of [18]. A projective variety is an algebraic variety that can be embedded into some projective space. Many number theoretic questions are nat- urally expressed as diophantine problems. Suppose that the algebraic variety X is de¯ned over the number ¯eld F . An algebraic dynamical system ' : X ! X is a ¯nite map from the algebraic variety X to itself. One of the tools to study algebraic dynamics over number ¯elds is the de¯nition of height functions. A (canonical) height function as- ^ ¹ sociated to ' is a function h' : X(F ) ! R, that attempts to compute the complexity of the point P 2 X(F¹) relative to the map '. For in- stance the points of ¯nite forward orbits for ' will be exactly the points ^ of height h'(P ) = 0. The notion of height can be also generalized to subvarieties Y ½ X, still measuring the behavior under iteration. -
The Circle Method
The Circle Method Steven J. Miller and Ramin Takloo-Bighash July 14, 2004 Contents 1 Introduction to the Circle Method 3 1.1 Origins . 3 1.1.1 Partitions . 4 1.1.2 Waring’s Problem . 6 1.1.3 Goldbach’s conjecture . 9 1.2 The Circle Method . 9 1.2.1 Problems . 10 1.2.2 Setup . 11 1.2.3 Convergence Issues . 12 1.2.4 Major and Minor arcs . 13 1.2.5 Historical Remark . 14 1.2.6 Needed Number Theory Results . 15 1.3 Goldbach’s conjecture revisited . 16 1.3.1 Setup . 16 2 1.3.2 Average Value of |FN (x)| ............................. 17 1.3.3 Large Values of FN (x) ............................... 19 1.3.4 Definition of the Major and Minor Arcs . 20 1.3.5 The Major Arcs and the Singular Series . 22 1.3.6 Contribution from the Minor Arcs . 25 1.3.7 Why Goldbach’s Conjecture is Hard . 26 2 Circle Method: Heuristics for Germain Primes 29 2.1 Germain Primes . 29 2.2 Preliminaries . 31 2.2.1 Germain Integral . 32 2.2.2 The Major and Minor Arcs . 33 2.3 FN (x) and u(x) ....................................... 34 2.4 Approximating FN (x) on the Major arcs . 35 1 2.4.1 Boundary Term . 38 2.4.2 Integral Term . 40 2.5 Integrals over the Major Arcs . 42 2.5.1 Integrals of u(x) .................................. 42 2.5.2 Integrals of FN (x) ................................. 45 2.6 Major Arcs and the Singular Series . 46 2.6.1 Properties of Arithmetic Functions . -
Report on Diophantine Approximations Bulletin De La S
BULLETIN DE LA S. M. F. SERGE LANG Report on Diophantine approximations Bulletin de la S. M. F., tome 93 (1965), p. 177-192 <http://www.numdam.org/item?id=BSMF_1965__93__177_0> © Bulletin de la S. M. F., 1965, tous droits réservés. L’accès aux archives de la revue « Bulletin de la S. M. F. » (http: //smf.emath.fr/Publications/Bulletin/Presentation.html) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/ conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright. Article numérisé dans le cadre du programme Numérisation de documents anciens mathématiques http://www.numdam.org/ Bull. Soc. math. France^ 93, ig65, p. 177 a 192. REPORT ON DIOPHANTINE APPROXIMATIONS (*) ; SERGE LANG. The theory of transcendental numbers and diophantine approxi- mations has only few results, most of which now appear isolated. It is difficult, at the present stage of development, to extract from the lite- rature more than what seems a random collection of statements, and this causes a vicious circle : On the one hand, technical difficulties make it difficult to enter the subject, since some definite ultimate goal seems to be lacking. On the other hand, because there are few results, there is not too much evidence to make sweeping conjectures, which would enhance the attractiveness of the subject. With these limitations in mind, I have nevertheless attempted to break the vicious circle by imagining what would be an optimal situa- tion, and perhaps recklessly to give a coherent account of what the theory might turn out to be. -
Small Dynamical Heights for Quadratic Polynomials and Rational Functions.1.1
Experimental Mathematics, 23:433–447, 2014 Copyright C Taylor & Francis Group, LLC ISSN: 1058-6458 print / 1944-950X online DOI: 10.1080/10586458.2014.938203 Small Dynamical Heights for Quadratic Polynomials and Rational Functions Robert L. Benedetto1, Ruqian Chen1, Trevor Hyde2, Yordanka Kovacheva3, and Colin White1 1Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts, USA 2Department of Mathematics, University of Michigan, Ann Arbor, Michigan, USA 3Department of Mathematics, University of Chicago, Chicago, Illinois, USA CONTENTS Let φ ∈ Q(z) be a polynomial or rational function of degree 2. A spe- 1. Introduction cial case of Morton and Silverman’sdynamical uniform boundedness 2. Background conjecture states that the number of rational preperiodic points of φ 3. Quadratic Polynomials is bounded above by an absolute constant. A related conjecture of 4. Quadratic Rational Functions Silverman states that the canonical height hˆφ (x) of a nonpreperiodic Acknowledgments rational point x is bounded below by a uniform multiple of the height Funding of φ itself. We provide support for these conjectures by computing References the set of preperiodic and small-height rational points for a set of degree-2 maps far beyond the range of previous searches. 1. INTRODUCTION In this paper, we consider the dynamics of a rational func- tion φ(z) ∈ Q(z) acting on P1(Q). The degree of φ = f/g is deg φ := max{deg f, deg g}, where f, g ∈ Q[z]haveno common factors. Define φ0(z) = z, and for every n ≥ 1, let Downloaded by [] at 10:38 03 August 2015 φn(z) = φ ◦ φn−1(z); that is, φn is the nth iterate of φ un- der composition. -
Mathematical Tripos Part III Lecture Courses in 2020-2021
Mathematical Tripos Part III Lecture Courses in 2020-2021 Department of Pure Mathematics & Mathematical Statistics Department of Applied Mathematics & Theoretical Physics Notes and Disclaimers. • Students may attend any combination of lectures but should note that it is not possible to take two courses for examination that are lectured in the same timetable slot. There is no requirement that students study only courses offered by one Department. • The code in parentheses after each course name indicates the term of the course (M: Michaelmas; L: Lent; E: Easter), and the number of lectures in the course. Unless indicated otherwise, a 16 lecture course is equivalent to 2 credit units, while a 24 lecture course is equivalent to 3 credit units. Please note that certain courses are non-examinable, and are indicated as such after the title. Some of these courses may be the basis for Part III essays. • At the start of some sections there is a paragraph indicating the desirable previous knowledge for courses in that section. On the one hand, such paragraphs are not exhaustive, whilst on the other, not all courses require all the pre-requisite material indicated. However you are strongly recommended to read up on the material with which you are unfamiliar if you intend to take a significant number of courses from a particular section. • The courses described in this document apply only for the academic year 2020-21. Details for subsequent years are often broadly similar, but not necessarily identical. The courses evolve from year to year. • Please note that while an attempt has been made to ensure that the outlines in this booklet are an accurate indication of the content of courses, the outlines do not constitute definitive syllabuses. -
Computing Points of Small Height for Cubic Polynomials
COMPUTING POINTS OF SMALL HEIGHT FOR CUBIC POLYNOMIALS ROBERT L. BENEDETTO, BENJAMIN DICKMAN, SASHA JOSEPH, BENJAMIN KRAUSE, DANIEL RUBIN, AND XINWEN ZHOU Abstract. Let φ Q[z] be a polynomial of degree d at least two. The associated ∈ canonical height hˆφ is a certain real-valued function on Q that returns zero precisely at preperiodic rational points of φ. Morton and Silverman conjectured in 1994 that the number of such points is bounded above by a constant depending only on d. A related conjecture claims that at non-preperiodic rational points, hˆφ is bounded below by a positive constant (depending only on d) times some kind of height of φ itself. In this paper, we provide support for these conjectures in the case d = 3 by computing the set of small height points for several billion cubic polynomials. Let φ(z) Q[z] be a polynomial with rational coefficients. Define φ0(z) = z, and for every n ∈ 1, let φn(z) = φ φn−1(z); that is, φn is the n-th iterate of φ under composition.≥ A point x is said to◦ be periodic under φ if there is an integer n 1 such that φn(x) = x. In that case, we say x is n-periodic; the smallest such positive≥ integer n is called the period of x. More generally, x is preperiodic under φ if there are integers n>m 0 such that φn(x)= φm(x); equivalently, φm(x) is periodic for some m 0. In 1950,≥ using the theory of arithmetic heights, Northcott proved that if deg≥φ 2, then φ has only finitely many preperiodic points in Q. -
Book-49693.Pdf
APPLICATIONS OF GROUP THEORY TO COMBINATORICS 2 SELECTED PAPERS FROM THE COM MAC CONFERENCE ON APPLICATIONS OF GROUP THEORY TO COMBINATORICS, POHANG, KOREA, 9–12 JULY 2007 Applications of Group Theory to Combinatorics Editors Jack Koolen Department of Mathematics, Pohang University of Science and Technology, Pohang 790–784, Korea Jin Ho Kwak Department of Mathematics, Pohang University of Science and Technology, Pohang 790–784, Korea Ming-Yao Xu Department of Mathematics, Peking University, Beijing 100891, P.R.China Supported by Com2MaC-KOSEF, Korea CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business © 2008 Taylor & Francis Group, London, UK Typeset by Vikatan Publishing Solutions (P) Ltd., Chennai, India Printed and bound in Great Britain by Anthony Rowe (A CPI-group Company), Chippenham, Wiltshire All rights reserved. No part of this publication or the information contained herein may be repro- duced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without written prior permission from the publisher. Although all care is taken to ensure integrity and the quality of this publication and the information herein, no responsibility is assumed by the publishers nor the author for any damage to the property or persons as a result of operation or use of this publication and/or the information contained herein. Published by: CRC Press/Balkema P.O. Box 447, 2300 AK Leiden, The Netherlands e-mail: [email protected] www.crcpress.com – www.taylorandfrancis.co.uk – www.balkema.nl ISBN: 978-0-415-47184-8 (Hardback) ISBN: 978-0-203-88576-5 (ebook) Applications of Group Theory to Combinatorics - Koolen, Kwak & Xu (eds) © 2008 Taylor & Francis Group, London, ISBN 978-0-415-47184-8 Table of Contents Foreword VII About the editors IX Combinatorial and computational group-theoretic methods in the study of graphs, maps and polytopes with maximal symmetry 1 M. -
UC Berkeley UC Berkeley Electronic Theses and Dissertations
UC Berkeley UC Berkeley Electronic Theses and Dissertations Title The arithmetic Hodge-index theorem and rigidity of algebraic dynamical systems over function fields Permalink https://escholarship.org/uc/item/4xb7w3f8 Author Carney, Alexander Publication Date 2019 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California The arithmetic Hodge-index theorem and rigidity of algebraic dynamical systems over function fields by Alexander Carney Adissertationsubmittedinpartialsatisfactionofthe requirements for the degree of Doctor of Philosophy in Mathematics in the Graduate Division of the University of California, Berkeley Committee in charge: Associate Professor Xinyi Yuan, Chair Associate Professor Burkhard Militzer Associate Professor Sug Woo Shin Spring 2019 The arithmetic Hodge-index theorem and rigidity of algebraic dynamical systems over function fields Copyright 2019 by Alexander Carney 1 Abstract The arithmetic Hodge-index theorem and rigidity of algebraic dynamical systems over function fields by Alexander Carney Doctor of Philosophy in Mathematics University of California, Berkeley Associate Professor Xinyi Yuan, Chair In one of the fundamental results of Arakelov’s arithmetic intersection theory, Faltings and Hriljac (independently) proved the Hodge-index theorem for arithmetic surfaces by relating the intersection pairing to the negative of the Neron-Tate height pairing. More recently, Moriwaki and Yuan–Zhang generalized this to higher dimension. In this work, we extend these results to projective varieties over transcendence degree one function fields. The new challenge is dealing with non-constant but numerically trivial line bundles coming from the constant field via Chow’s K/k-image functor. As an application of the Hodge-index theorem to heights defined by intersections of adelic metrized line bundles, we also prove a rigidity theorem for the set height zero points of polarized algebraic dynamical systems over function fields. -
Rationality of Dynamical Canonical Height 11
RATIONALITY OF DYNAMICAL CANONICAL HEIGHT LAURA DE MARCO AND DRAGOS GHIOCA Abstract. We present a dynamical proof of the well-known fact that the N´eron-Tate canonical height (and its local counterpart) takes rational values at points of an elliptic curve over a function field k = C(X), where X is a curve. More generally, we investigate the mechanism for which the local canonical height for a map f : P1 ! P1 defined over a function field k can take irrational values (at points in a local completion of k), providing examples in all degrees deg f ≥ 2. Building on Kiwi's classification of non-archimedean Julia sets for quadratic maps [Ki1], we give a complete answer in degree 2 characterizing the existence of points with irrational local canonical heights. As an application we prove that if the heights bhf (a); bhg(b) are rational and positive, for maps f and g of multiplicatively 1 ¯ n m independent degrees and points a; b 2 P (k), then the orbits ff (a)gn≥0 and fg (b)gm≥0 intersect in at most finitely many points, complementing the results of [GTZ1]. 1. Introduction Throughout this article, we let K be an algebraically closed field of characteristic 0, X a smooth projective curve defined over K, and k = K(X) its function field. We examine the values of the canonical height function associated to dynamical systems 1 1 f : P ! P defined over k, of degree deg(f) ≥ 2. The canonical height bhf was introduced in [CS] for general polarized dynamical systems f on projective varieties. -
Diophantine-Geometry-Course.Pdf
DIOPHANTINE GEOMETRY { TAUGHT BY JOE SILVERMAN NOTES BY SHAMIL ASGARLI 1. Diophantine Equations Objective. Solve polynomial equations using integers (or rationals). Example. Linear equation: Solve ax + by = c where a; b; c 2 Z. It is a classical fact from elementary number theory that this equation has a solution (for x and y) if and only if gcd(a; b) j c. Example. Quadratic equation: x2 + y2 = z2. We are interested in non-zero solutions (x; y; z) 2 Z, i.e. (x; y; z) 6= (0; 0; 0). Since the equation is homogeneous, it is enough to understand the solutions of X2 + Y 2 = 1 where X; Y 2 Q (points on the unit circle). Anyways, the complete solution is known for this problem. WLOG gcd(x; y; z) = 1, x is odd and y is even. Then the solutions are given by x = s2 − t2, y = 2st, and z = s2 + t2. s2 − t2 Analogously, the solutions (X; Y ) 2 2 of X2 + Y 2 = 1 are parametrized by: X = Q s2 + t2 2st and Y = . s2 + t2 Example. Consider the equation y2 = x3 − 2. It turns out that (3; ±5) are the only solutions in Z2, while there are infinitely many solutions (x; y) 2 Q. Goal. Given f1; f2; :::; fk 2 Z[X1; :::; Xn]. For R = Z; Q, or any other ring. Let n V (R) = f(x1; x2; :::; xn) 2 R : fi(x1; :::; xn) = 0 for all ig Describe V (R). Two questions naturally arise. 1) Is V (R) = ;? This is undecidable for R = Z. 2) Is V (R) finite? 2 variables, 1 equation.