Effectivity for existence of rational points is undecidable

Abstract

The analogue of Hilbert's tenth problem over $Q$ asks for an algorithm to decide the existence of rational points on algebraic varieties over this field. This remains as one of the main open problems in the area of undecidability in number theory. Besides the existence of rational points, there is also considerable interest in the problem of effectivity: one asks whether the sought rational points satisfy determined height bounds, often expressed in terms of the height of the coefficients of the equations defining the algebraic varieties under consideration. We show that, in fact, Hilbert's tenth problem over $Q$ with (finitely many) height comparison conditions is undecidable.