“…Within the system NEKST the following types of semantic transformations have been implemented: -user suggestions [22], -substitution with synonyms, hypernyms, hyponyms and other related concepts, -concept disambiguation [3], -document categorization [3], -personalized PageRank [15], -cluster analysis and assignment of cluster keywords to documents [2], -explicit separation of document cluster and document search, -extraction of named entities and relations between them [23], -diversification of responses to queries, -dynamic summarizing [13], and -identification and classification of harmful contents.…”