Dynamic maintenance of bichromatic closest pair

Let A and B be two sets of points in the plane. The bichromatic closest
pair is a pair (p,q) in AxB that minimizes d(p,q). The goal is to maintain
a bichromatic closest pair when points are inserted or deleted from A or 
B.  I will present a clever algorithm by Eppstein for this problem. In 
fact, the algorithm is very generic and can be applied to a wide range of 
problems (e.g., dynamic maintenance of extrema of binary functions).