APPARATUS AND METHOD FOR INFORMATION RETRIEVAL USING SELF-APPENDING SEMANTIC LATTICE

An information retrieval apparatus retrieves information from databases comprising internal representations of documents. Syntactic relations between terms of the query are extracted and an internal representation of the query is created based on the terms of the query and the extracted syntactic relations. New terms are appended to a semantic lattice if the query includes terms not included in the semantic lattice. The query is projected onto the documents in the database by comparing the internal representation and terms of the query to the internal representations and terms of the documents using the semantic lattice for comparing the terms and a similarity is computed between the query and each document. The documents are ranked according to their computed similarities and are output as retrieved documents according to the established rank order.