PageRank： http://en.wikipedia.org/wiki/Page_rank ; http://download.csdn.net/source/376367
BM25：http://download.csdn.net/source/376362
RankBoost: http://download.csdn.net/source/376396
PRanking: http://download.csdn.net/source/376367
RankSVM: http://download.csdn.net/source/376391
RankNet：http://download.csdn.net/source/376365
AdaRank：http://download.csdn.net/source/376370
RankCosine：http://download.csdn.net/source/376372
