Abstract: A method, apparatus and machine-readable medium analyze documents processed by non-negative matrix factorization in accordance with semantic topics. Users construct queries by assigning weights to semantic topics to order documents within a set. The query may be refined in accordance with the user's evaluation of the efficacy of the query. Any document that does not result in data indicative of significant correlation with at least one semantic topic is flagged so that a user may make a manual review. The collection of semantic topics may be continually or periodically updated in response to new documents. Additionally, the collection may also be “downdated” to drop semantic factors no longer appearing in new documents received after an initial set has been analyzed. Different sets of semantic topics may be generated and each document evaluated using each set. Reports may be prepared showing results for a body of documents for each of a plurality of sets of semantic topics.