13. One or more computer-readable storage devices comprising computer executable instructions that, when executed, direct a computing system to perform acts, the acts comprising: re-weighting documents in a corpus based at least in part on a latent topic to identify one or more concepts associated with the documents, the re-weighting comprising strengthening a subset of the documents that are indicated by the latent topic by adjusting document weights to increase a term frequency of each of one or more terms within the subset of the documents associated with the latent topic; evaluating, based in part on the increase of the term frequency of each of the one or more terms, a modified latent semantic analysis (LSA)-weighted frequency of one or more documents of the subset of the documents to identify one or more topic phrases associated with the latent topic; and filtering the documents associated with similar concepts to result in a document collection with unlike concepts.
13. One or more computer-readable storage devices comprising computer executable instructions that, when executed, direct a computing system to perform acts, the acts comprising: re-weighting documents in a corpus based at least in part on a latent topic to identify one or more concepts associated with the documents, the re-weighting comprising strengthening a subset of the documents that are indicated by the latent topic by adjusting document weights to increase a term frequency of each of one or more terms within the subset of the documents associated with the latent topic; evaluating, based in part on the increase of the term frequency of each of the one or more terms, a modified latent semantic analysis (LSA)-weighted frequency of one or more documents of the subset of the documents to identify one or more topic phrases associated with the latent topic; and filtering the documents associated with similar concepts to result in a document collection with unlike concepts. 14. The one or more computer-readable storage devices of claim 13 , wherein the re-weighting further comprises: selecting one or more additional latent topics from the corpus, each latent topic being characterized by a singular value, wherein each singular value indicates a relevance of concepts associated with the documents; arranging the latent topics based on the singular values; and extracting at least one phrase from one or more of the latent topics.