19. The computer readable storage medium of claim 15 , wherein performing the one or more analysis procedures includes significance analysis of each URL parameter associated with the cluster.
15. The computer readable storage medium of claim 14 , wherein said equivalence rule generator including instructions for: performing one or more analysis procedures for each of the URL parameters associated with the cluster; deriving from said analysis procedures one or more values indicative of a relationship pattern between the URL parameter and its associated document contents; and classifying the URL parameter into one of multiple categories in accordance with its values.