11. A method for thematically grouping documents into clusters, comprising the steps of: extracting from a plurality of documents, concepts comprising at least one of nouns and noun phrases; determining a number of occurrences for each concept within each document; selecting the documents having the concepts with the occurrences that satisfy a bounded range comprising upper edge conditions and lower edge conditions; generating themes for the selected documents from the subset of concepts by identifying two or more concepts with common semantic meaning; and generating clusters of the selected documents based on the themes, wherein the steps are performed by a suitably programmed computer.
19. A method according to claim 11 , further comprising: generating a database record for each concept comprising a concept identifier, string, and occurrence frequency.