... parame-ters for a keyword extractor embedded in the Ex-tractor tool.3Or˘asan et al. (2000) enhanced thepreference-based anaphora resolution algorithmsby using a GA to find an optimal set ... op-eration.3http://www.extractor.com/928Today, graph-based text representations are be-coming increasingly popular, due to their abil-ity to enrich the document model with syntacticand semantic relations. Salton ... number of keywordsand the total number of words in the ithcluster, re-spectively, such that clusters are portions of a sen-tence bracketed by keywords, i.e., frequent, non-common words.4Figure...