Microsoft - A learning method is used to generate ranking models. The learning method can create a ranking function that assigns scores to documents and then ranks the documents using the scores. In this learning method, a training set along with performance measures are used to generate weak rankers which a used in the ranking model.During information retrieval, for a given query, the system may return a ranked list of documents in descending order of the relevance scores.

Yahoo 2007 - Described are a system and method for selecting a training sample from a sample set. The method comprises determining proximities between all data samples in a set of the data samples, forming edges between the data samples as a function of the proximities, computing weights for the edges as a function of the proximities, selecting a plurality of the data samples as a function of the weights to form a subset of the data samples, and storing the subset of the data samples.