3. The method of claim 1 , wherein assigning the scores, selecting the set of documents, and presenting the information identifying the set of documents to the user are performed in response to a request from the user to obtain the set of documents.
1. A processor-implemented method, comprising: receiving an input from a user identifying an initial document in a collection of documents; identifying other documents in the collection of documents that are related to the initial document, comprising: assigning scores to a plurality of compressed document surrogates corresponding to the collection of documents, the scores depending on an occurrence in the compressed document surrogates of at least one term in the initial document, wherein a score S D of a compressed document surrogate D in the plurality of compressed document surrogates is determined by crediting the compressed document surrogate D, for each term T in the initial document which occurs in the compressed document surrogate D, with an amount proportional to Robertson's term frequency TF TD and to IDF T where 
 TF TD =N TD /( N TD +K 1 +K 2 *( L D /L 0 )),and N TD is the number of times the term T occurs in compressed document surrogate D, L D is the length of compressed document surrogate D, L 0 is the average length of a document in the collection of documents, K 1 and K 2 are constants, and 
 IDF T = log((N+K 3 )/N T )/log(N+K 4 ), and N is the number of documents in the collection of documents, N T is the number of documents containing the term T in the collection of documents, and K 3 and K 4 are constants; selecting a set of documents from the collection of documents, the set of documents comprising documents corresponding to those of the plurality of compressed document surrogates assigned the highest scores; and presenting information identifying the set of documents to the user.