Before revision: The problem of nearest-neighbor  condensation deals with finding a subset R from a set of labeled points P such that for every point p \in P the nearest-neighbor of p in R has the same label as p.
After revision: The problem of nearest-neighbor rule predicts the class of an unlabeled query point as the label of its closest point in the set. To improve the time and space complexity of classification, a natural question is how to reduce the training set without significantly affecting the accuracy of the nearest-neighbor rule. Nearest-neighbor condensation deals with finding a subset R from a set of labeled points P such that for every point p \in P the nearest-neighbor of p in R has the same label as p.