HITS Algorithm
Hypertext Induced Topic Selection Algorithm
The HITS ("hypertext induced topic selection") algorithm is an algorithm for rating, (J.Kleinberg) and therefore also ranking, Web pages. HITS uses two values for each page, the authority value and the hub value. Authority and hub values are defined in terms of one another in a mutual recursion. An authority value is computed as the sum of the scaled hub values that point to that page. A hub value is the sum of the scaled authority values of the pages it points to. Relevance of the linked pages is also considered in some implementations. J. Kleinberg�s algorithm is similar to PageRank, in that it is an iterative algorithm based purely on the linkage of the documents on the web. However it does have some major differences: It is executed at query time, and not at indexing time, with the associated hit on performance that accompanies query-time processing. It is not commonly used by search engines. It computes two scores per document (hub and authority) as opposed to a single score. It is processed on a small subset of �relevant� documents, not all documents as was the case with PageRank.