A reduction of the Batyrev-Manin Conjecture for Kummer Surfaces

Let V be a K3 surface defined over a number field k. The BatyrevManin conjecture for V states that for every nonempty open subset U of V , there exists a finite set ZU of accumulating rational curves such that the density of rational points on U − ZU is strictly less than the density of rational points on ZU . Thus, the set of rational points of V conjecturally admits a stratification corresponding to the sets ZU for successively smaller sets U . In this paper, in the case that V is a Kummer surface, we prove that the Batyrev-Manin conjecture for V can be reduced to the Batyrev-Manin conjecture for V modulo the endomorphisms of V induced by multiplication by m on the associated abelian surface A. As an application, we use this to show that given some restrictions on A, the set of rational points of V which lie on rational curves whose preimages have geometric genus 2 admits a stratification of Batyrev-Manin type.