  Partly because of the difficulty of communications between Siberia and the West, these results of Zilber took some time to digest, and in part they had to be rediscovered in the West. But when the message did finally get through, the result was a new branch of model theory which has come to be known as geometric model theory. The programme is broadly to classify structures according to (a) what groups or fields are interpretable in them (in the sense sketched in the entry  on  model theory)  and (b) whether or not the structures have ‘modular geometries’; and then to use this classification to solve problems in model theory and geometry. From the mid 1980s the leader of this research was Ehud Hrushovski. In the early 1990s, using joint work with Zilber, Hrushovski gave a model-theoretic proof (the first complete proof to be found) of the geometric Mordell-Lang conjecture in all characteristics; this was a conjecture in classical diophantine geometry. Bouscaren (ed.) 1998 is devoted to Hrushovski’s proof and the necessary background in model theory. Both (a) and (b) are fundamental to Hrushovski’s argument.