EXTENDED BOOLEAN OPERATIONS IN LATENT SEMANTIC INDEXING SEARCH

The paper presents a method for the usage of Boolean expressions for information retrieval based on Latent Semantic Indexing (LSI). The basic binary Boolean expressions such as OR, AND and NOT (AND-NOT) and their combinations have been implemented. The proposed method adds a new functionality to the classic LSI method capabilities to process user queries typed in a natural language (such as English, Bulgarian or Russian) used in the “intelligent” search engines. This gives the user the opportunity of combining not only distinct words or phrases, but also whole texts (documents) using all kinds of Boolean expressions. An evaluation of the implementations has been performed using a text collection of religious and sacred texts.