Bounded height theorems in arithmetic dynamics
Let r be a positive integer, and let f1,..,fr∈ˉQ[x] be polynomials of degrees larger than 1 such that no fi is conjugated to a monomial xd or to ±Cd(x) (where Cd(x) is the d-th Chebyshev polynomial). We denote by Φ the coordinatewise action of the polynomials f1,…,fr on (P1)r.
Let X be an irreducible subvariety of (P1)r of dimension d defined over ˉQ. We define the Φ-anomalous locus of X which is related to the Φ-periodic subvarieties of (P1)r. We prove that the Φ-anomalous locus of X is Zariski closed, which is a dynamical analogue of a theorem of Bombieri, Masser, and Zannier. We also prove that the points in the intersection of X with the union of all irreducible Φ-periodic subvarieties of (P1)r of codimension d have bounded height outside the Φ-anomalous locus of X, which is a dynamical analogue of a theorem of Habegger.
This is joint work with Khoa Nguyen.