1. A method for accessing documents related to a subject from a document corpus, comprising: creating a candidate list of word sequences, respective ones of the word sequences comprising one or more elements derived from the document corpus; expanding the candidate list by adding one or more new word sequences, wherein each new pattern is created by combining one or more elements derived from the document corpus with one of said word sequences; determining a predictive power with respect to the subject for respective ones of entries of the candidate list, wherein the entries comprise said word sequences and said new word sequences; pruning from the candidate list ones of said entries with the determined predictive power less than a predetermined threshold; and accessing documents from the document corpus based on the pruned candidate list.