19. A computer-implemented method for matching a query from a user to at least one document in a database based on a sequence of topic words stored for each document in the database, the method comprising the steps of: accepting the query from a data input device; parsing the query to form query keywords which satisfy a predetermined definition of domain keywords; computing a closeness score between the parsed query and the topic words for each of a plurality of documents in the database using an entropy-based metric; and sorting the computed closeness score of at least two of the plurality of documents in the database.
20. The method according to claim 19 wherein the step of computing a closeness score comprises the steps of: classifying each of the query keywords into one of a plurality of preestablished keyword classes; and computing as the closeness score a conditional likelihood of appearance by the query keywords given appearance by the topic words of one of the plurality of documents in the database.