Hitachi, Ltd.

Osamu Imaichi

Makoto Iwayama

Tomohiro Yasuda

Toru Hisamitsu

Hiroyuki Kaji

Yoshiki Niwa

Shingo Nishioka

Kazutomo Ushijima

Tetsuo Nishikawa

Masakazu Fujio

Yasutsugu Morimoto

To achieve high speed document search, an inverted index is compressed at high compressibility by an encoding method decodable in a high process speed. In compressing an identification number of a document to obtain a byte sequence by the variable byte method, w bits are used to represent the number of occurrences of the indexing term in the document, and x bits are used to represent additional information of the posting, where x and w are integers given as parameters. When the number of occurrences cannot be represented within w bits, a certain value indicating a numeric value that cannot be represented by w bits is stored is written to the said w bits, and anther byte sequence that represents the value by the variable byte method follows. Additionally provided is a means for reading a compressed posting from any position of a list of postings called inverted lists, allowing a binary search on an inverted list.

Device and method for constructing inverted indexes

In document search for searching a document by use of a query formula composed of a Boolean formula of keywords, a plurality of query formulas arriving at about the same time from a plurality of users are efficiently processed. A system or a program for searching documents includes: a query formula controller for sorting a plurality of query formulas into a plurality of query formula sets based on predicted search speeds of the respective query formulas; and a search unit for searches for the plurality of sorted query formula sets sequentially from the set having the fastest predicted search speed, and for, in each search processing, merging the query formulas in the corresponding query formula set into a formula and thereby searching from the merged formula.

System or program for searching documents

A document search apparatus capable of an index-type search and a scan-type search performs a search in a combination of the two search types while compensating for the disadvantages of the two search types with each other. A search query for index-type search and a search query for scan-type search are constructed based on a search query consisting of a logical formula of keywords. Then, a character 2-gram for performing an index search is set to shorten the whole search time, and the index-type search is performed. Finally, a scan-type search is performed on this search result of the index-type search.

Document search method and document search apparatus that use a combination of index-type search and scan-type search

A text classification apparatus directed to a plurality of languages, includes a unit for extracting information for converting a word from non-classified (unlabeled) texts, in a plurality of languages, into a word sense, a unit for learning a classification knowledge at a word sense level after converting a word extracted from a labeled text into a word sense, a unit for learning a classification knowledge at a word level from the labeled text, a unit for learning the classification knowledge at the word level from the classification knowledge at the word sense level and information on a relation between words extracted from the unlabeled text, and a unit for combining the respective classification knowledges to assign a category.

Cross lingual text classification apparatus and method

Ordering is properly performed for document databases registered in an associative search server. In an associative search server capable of performing an associative search by correlating a plurality of document databases, the history of the associative search is stored as an associative search recording table by associative search recording table storing means. By using this associative search recording table, a showing order of document databases presented by document database selecting means is properly set by showing order changing means. Alternatively, by registration fee calculating means, calculation is properly carried out as to registration fees of the document database registered in the associative search server.

Document retrieval system and search server

A system allows related documents to be retrieved using conventional search engines while overcoming the ambiguity of a search key entered by the user. The system includes a word sense associative network display portion for displaying word senses of the search key entered by the user together with related word senses in a network, a search portion for conducting a search by generating a search key based on word senses selected by the user, and a filtering portion for selecting documents from the result of the search that matches the selected word sense.

Document search system using a meaning relation network

A system for displaying the results of a search provided by one of two different search systems enabling continuous searching. One search system includes a search takeover data production command used to output search takeover data articles from the search. The other search system includes a search takeover data reading command used to read search takeover data. A document identifier correspondence table associates the identifiers specified in the search takeover data. When a user clicks a search system transfer instruction button in one search system, the search takeover data producing command is executed to produce search takeover data which is passed to the other search system. The latter search system regards the list of identifiers of articles which was passed by the search takeover data reading command as the search results, and thus operates continuously.

Search system

The present invention visualizes the contents of a plurality of documents without a lack of the listing property. Two document units are extracted from a document database and relevance degrees between individual elements of a group of the document units are calculated. The results are displayed on a two-dimensional coordinate plane depending on the relevance degree.

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Wako, Japan

Osamu Imaichi