Description
This book considers the so-called Unlikely Intersections, a topic that embraces well-known issues, such as Lang's and Manin-Mumford's, concerning torsion points in subvarieties of tori or abelian varieties. More generally, the book considers algebraic subgroups that meet a given subvariety in a set of unlikely dimension. The book is an expansion of the Hermann Weyl Lectures delivered by Umberto Zannier at the Institute for Advanced Study in Princeton in May 2010.
The book consists of four chapters and seven brief appendixes, the last six by David Masser. The first chapter considers multiplicative algebraic groups, presenting proofs of several developments, ranging from the origins to recent results, and discussing many applications and relations with other contexts. The second chapter considers an analogue in arithmetic and several applications of this. The third chapter introduces a new method for approaching some of these questions, and presents a detailed application of this (by Masser and the author) to a relative case of the Manin-Mumford issue. The fourth chapter focuses on the André-Oort conjecture (outlining work by Pila).
Chapter
1 Unlikely Intersections in Multiplicative Groups and the Zilber Conjecture
1.1 Torsion points on subvarieties of G
1.2 Higher multiplicative rank
1.3 Remarks on Theorem 1.3 and its developments
1.3.1 Fields other than Q
1.3.2 Weakened assumptions
1.3.3 Unlikely intersections of positive dimension and height bounds
1.3.4 Unlikely intersections of positive dimension and Zilber’s conjecture
1.3.5 Unlikely intersections and reducibility of lacunary polynomials (Schinzel’s conjecture)
1.3.6 Zhang’s notion of dependence
1.3.7 Abelian varieties (and other algebraic groups)
1.3.8 Uniformity of bounds
Sparseness of multiplicatively dependent points
Other unlikely intersections
A generalization of Theorem 1.3
An application of the methods to zeros of linear recurrences
2 An Arithmetical Analogue
2.1 Some unlikely intersections in number fields
2.2 Some applications of Theorem 2.1
2.3 An analogue of Theorem 2.1 for function fields
2.4 Some applications of Theorem 2.2
2.5 A proof of Theorem 2.2
Simplifying the proof of Theorem 1.3
Rational points on curves over F
Unlikely Intersections and Holomorphic GCD in Nevanlinna Theory
3 Unlikely Intersections in Elliptic Surfaces and Problems of Masser
3.1 A method for the Manin-Mumford conjecture
3.2 Masser’s questions on elliptic pencils
3.4 Related problems, conjectures, and developments
3.4.1 Pink’s and related conjectures
3.4.2 Extending Theorem 3.3 from Q to C
3.4.4 Extending Theorem 3.3 to arbitrary pairs of points on families of elliptic curves
3.4.5 Simple abelian surfaces and Pell’s equations over function fields
3.4.6 Further extensions and analogues
3.4.7 Dynamical analogues
Torsion values for a single point: other arguments
A variation on the Manin-Mumford conjecture
4 About the André-Oort Conjecture
4.1 Generalities about the André-Oort Conjecture
4.2 Modular curves and complex multiplication
4.3.1 An effective variation
4.4 Pila’s proof of André’s theorem
Remarks on Edixhoven’s approach to André’s theorem
Some unlikely intersections beyond André-Oort
Definability and o-minimal structures
Appendix A Distribution of Rational Points on Subanalytic Surfaces
Appendix B Uniformity in Unlikely Intersections: An Example for Lines in Three Dimensions
Appendix C Silverman’s Bounded Height Theorem for Elliptic Curves: A Direct Proof
Appendix D Lower Bounds for Degrees of Torsion Points: The Transcendence Approach
Appendix E A Transcendence Measure for a Quotient of Periods
Appendix F Counting Rational Points on Analytic Curves: A Transcendence Approach
Appendix G Mixed Problems: Another Approach