Hi Koji, strictly talking about TF-IDF ( and BM25 which is an evolution of that approach) I would say it is a weighting function/numerical statistic that can be used for ranking functions and is based on probabilistic concepts ( such as IDF) but it is not a probabilistic function[1]. Indeed a BM25 score for a term is not assured to be 0<x<1
Furthermore Lucene and Solr adds a lot on top of the BM25 similarity ( including different kind of boost( document, field and query time boost, norms, coord ) so they use probabilistic concepts but they are not probabilistic search engine. [1] http://math.stackexchange.com/questions/610165/prove-that-the-bm25-scoring-function-is-probabilistic ----- --------------- Alessandro Benedetti Search Consultant, R&D Software Engineer, Director Sease Ltd. - www.sease.io -- View this message in context: http://lucene.472066.n3.nabble.com/Filtering-results-by-minimum-relevancy-score-tp4329180p4329715.html Sent from the Solr - User mailing list archive at Nabble.com.
