Before revision:  We study this problem in the {\em k-machine model}, Note that parameter k stands for the number of machines in the k-machine model and is independent of K-nearest points. a model for distributed large-scale data.
After revision:  We study this problem in the {\em k-machine model}, (Note that parameter k stands for the number of machines in the k-machine model and is independent of K-nearest points.) a model for distributed large-scale data.