One-basedness and reductions of elliptic curves over real closed fields

Abstract

Building on the positive solution of Pillay's conjecture we present a notion of "intrinsic" reduction for elliptic curves over a real closed field K. We compare such notion with the traditional algebro-geometric reduction and produce a classification of the group of K-points of an elliptic curve E with three "real" roots according to the way E reduces (algebro-geometrically) and the geometric complexity of the "intrinsically" reduced curve.