{ "id": "1305.0222", "version": "v3", "published": "2013-05-01T16:47:36.000Z", "updated": "2014-05-03T23:34:23.000Z", "title": "The Arithmetic of Curves Defined by Iteration", "authors": [ "Wade Hindes" ], "comment": "24 pages", "categories": [ "math.NT" ], "abstract": "We show how the size of the Galois groups of iterates of a quadratic polynomial $f(x)$ can be parametrized by certain rational points on the curves $C_n:y^2=f^n(x)$ and their quadratic twists. To that end, we study the arithmetic of such curves over global and finite fields, translating key problems in the arithmetic of polynomial iteration into a geometric framework. This point of view has several dynamical applications. For instance, we establish a maximality theorem for the Galois groups of the fourth iterate of quadratic polynomials $x^2+c$, using techniques in the theory of rational points on curves. Moreover, we show that the Hall-Lang conjecture on integral points of elliptic curves implies a Serre-type finite index result for these dynamical Galois groups, and we use conjectural bounds for the Mordell curves to predict the index in the still unknown case when $f(x)=x^2+3$. Finally, we provide evidence that these curves defined by iteration have geometrical significance, as we construct a family of curves whose rational points we completely determine and whose geometrically simple Jacobians have complex multiplication and positive rank.", "revisions": [ { "version": "v3", "updated": "2014-05-03T23:34:23.000Z" } ], "analyses": { "keywords": [ "arithmetic", "galois groups", "rational points", "quadratic polynomial" ], "note": { "typesetting": "TeX", "pages": 24, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1305.0222H" } } }