The classification of rational preperiodic points of quadratic polynomials over \(\mathbb{Q}\): A refined conjecture. (English) Zbl 0902.11025

The author classifies the graphs that can occur as the graph of rational preperiodic points of a quadratic polynomial over \(\mathbb{Q}\), assuming the conjecture that it is impossible to have rational points of period 4 or higher. In particular, he shows under this assumption that the number of preperiodic points is at most 9. Elliptic curves of small conductor and the genus 2 modular curves \(X_1(13)\), \(X_1(16)\), and \(X_1(18)\) all arise as curves classifying quadratic polynomials with various combinations of preperiodic points. To complete the classification, he computes the rational points on a non-modular genus 2 curve by performing a 2-descent on its Jacobian and afterwards applying a variant of the method of Chabauty and Coleman.


11G30 Curves of arbitrary genus or genus \(\ne 1\) over global fields
37C25 Fixed points and periodic points of dynamical systems; fixed-point index theory; local dynamics
11G10 Abelian varieties of dimension \(> 1\)
14H40 Jacobians, Prym varieties
Full Text: DOI arXiv