Abstract: Word boundary identification operations such as morpheme analysis is performed on documents to be registered, and the top positions and the end positions of words are identified. Word boundary information is obtained based on these identification results. Search indexes are created for sub-strings of a predetermined length (n-grams) extracted from the document being registered. The search index includes document identification information as well as occurrence position information which indicates that the string is located at the n-th position from the beginning of the text data, and word boundary information for an n-gram in a document.

Abstract: A registration/search method for structured documents where correspondence data is prepared between a fixed-length-string and a string occurrence position within a structured document for all fixed-length-strings in the document and for each structured document. A list of a character and all hierarchical elements containing the character and element lengths is prepared. An occurrence frequency and an occurrence position of a search term is obtained using the plurality of fixed-length-substrings and the occurrence frequency extracting index. A search character is selected from the search term. A hierarchical element containing the search character is obtained using the character from the element length index. A length of the element corresponding to a search range is extracted using the obtained occurrence position. A matching degree for the search term is calculated from the obtained occurrence frequency of the search term and the extracted element length of the element corresponding to the search range.

Abstract: Word boundary identification operations such as morpheme analysis is performed on documents to be registered, and the top positions and the end positions of words are identified. Word boundary information is obtained based on these identification results. Search indexes are created for sub-strings of a predetermined length (n-grams) extracted from the document being registered. The search index includes document identification information as well as occurrence position information which indicates that the string is located at the n-th position from the beginning of the text data, and word boundary information for an n-gram in a document.

Abstract: A registration method for structured documents includes the steps of: preparing correspondence data between a string and a string occurrence position within a structured document for each structured document, and additionally storing the correspondence data in an occurrence frequency extracting index; and preparing a list of a character, an element containing the character and a length of the element and additionally storing the list in an element length index.

Abstract: A registration method for structured documents includes the steps of: preparing correspondence data between a string and a string occurrence position within a structured document for each structured document, and additionally storing the correspondence data in an occurrence frequency extracting index; and preparing a list of a character, an element containing the character and a length of the element and additionally storing the list in an element length index.

Abstract: A method for extracting features in contents of a document without using a word dictionary and a system using the method for accurately searching for a relevant document or documents at high speed. The method includes steps of storing character strings present in a text in a text database and possibilities appearing at boundaries of words in the text in the form of an occurrence probability file, storing occurrence frequencies of the character strings in the text as an occurrence frequency file, extracting characteristic strings from a text spcified by a user with use of the occurrence probability file, and counting occurrence frequencies thereof in the user-specified text. The method calculates similarities to the user-specified text with use of the occurrence frequency file and the occurrence frequencies in the user-specified text.

Abstract: A text data registering and retrieving method capable of improving the transaction processing performance is provided. The document number of a document for which deletion or replacement has been newly requested is registered in an updated document number list. The text data of the document for which insertion or replacement has been newly requested is registered in an update text buffer. The text data stored temporarily in the update text buffer is registered in a plural-character occurrence file defining a text index in a character component file merge step. The data registered in the plural-character occurrence file is retrieved for query terms. The text data stored in the update text buffer is retrieved for the query terms. The document number of a document updated or deleted is deleted from the result of retrieval in the plural-character occurrence file. Also, the result or the document number obtained in the, update text buffer is added to the result of retrieval to provide a final retrieval result.