说明：  Knn算法综述、柔性KNN算法研究、一个高效的knn分类算法、一种改进的KNN分类算法、一种优化的K最近邻协同过滤算法。
(Algorithms Knn, flexible KNN algorithm, an efficient knn classification algorithm, an improved KNN classification algorithm, an optimized K-nearest neighbor collaborative filtering algorithms.)