Abstract: A method, a system and a computer program for extracting information from a natural language text corpus based on a natural language query are disclosed. The natural language text corpus is indexed and stored. A natural language query is analyzed with respect to phrases, phrase types, syntactic roles, word tokens of phrases, and lexical meaning of word tokens. One or more surface variants are created for at least one phrase of the natural language query. The one or more surface variants each have the same phrase type as the at least one phrase of the natural language query, and each comprise a word token which is a lexical head and has the same lexical meaning as a word token which is a lexical head of the at least one phrase of the natural language query. The one or more surface variants and the at least one phrase of the natural language query are compared with the indexed and stored natural language text corpus.

Abstract: A method and a system for automatically finding one or more answers to a natural language question in a computer stored natural language text database is disclosed. The natural language text database has been analyzed with respect to syntactic functions of constituents, lexical meaning of word tokens and clause boundaries, and the natural language question comprises a question clause. A computer readable representation of the question clause is analyzed with respect to syntactic functions of its constituents and the lexical meaning of its word tokens. In response to the analysis a set of conditions for a clause in the natural language text database to constitute an answer to the question clause is defined. The conditions relate to the syntactic functions of constituents and the lexical meaning of word tokens in the clause.

Abstract: A method and a system for extracting information from a natural language text corpus based on a natural language query are disclosed. In the method the natural language text corpus is analyzed with respect to surface structure of word tokens and surface syntactic roles of constituents, and the analyzed natural language text corpus is then indexed and stored. Furthermore a natural language query is analyzed with respect to surface structure of word tokens and surface syntactic roles of constituents. From the analyzed natural language query one or more surface variants are then created, where these surface variants are equivalent to the natural language query with respect to lexical meaning of word tokens and surface syntactic roles of constituents.