Hitachi, Ltd.

Michio Iijima

Atsushi Hatakeyama

Natsuko Sugaya

Tadataka Matsubayashi

Shinya Yamamoto

Yuichi Ogawa

Yukio Nakano

Masaki Yotsutani

Yuuki Watanabe

Tsuyoshi Sudou

A document retrieval system includes a storage device and a retrieval server. The storage device stores document data including documents compressed so as to correspond to a plurality of divided document groups, indexes indicating correspondence relations between partial character strings for retrieving the documents and first identifiers indicating the documents, and a first correspondence table in which the document groups are divided into document small groups, and second identifiers which indicate the document small groups correspond to the partial character strings. The retrieval server retrieves, in response to an input of a retrieval character string, a second identifier corresponding to a partial character string included in the retrieval character string, from the first correspondence table, decompresses document data in a document group, retrieves a first identifier corresponding to the partial character string, obtains document data corresponding to the retrieved first identifier, and outputs the retrieved first identifier.

Document retrieval system and retrieval method

A data search method and system are provided in which data including a suitable reply to a query can be retrieved through a concept search. A data search method for searching for a text group that is similar to an inquiry text from data storing a plurality or text groups into which a plurality of texts are grouped includes: obtaining first information that is likely to be a search object and an appearance frequency of the first information with respect to each of the text groups and classifying the first information as second information that is a search object if the appearance frequency of the first information is less than or equal to a predetermined frequency; extracting third information included in the inquiry text; searching for the third information from the second information with respect to each of the text groups; and outputting the identifiers of a predetermined number of text groups with a higher number of hits on the third information included in the inquiry text.

Data search method and data search system

This string search method for a computer that searches documents for a specified string includes the following steps: a first step in which the specified string is divided into a plurality of characters or strings, including a first character or string and a second character or string; a second step in which a plurality of sets are created by grouping a plurality of documents in units; a third step in which a determination is made as to whether or not the first character or string appears in that set; a fourth step in which a determination is made as to whether or not the second character or string appears in that set; and a sixth step in which, if first appearance information and second appearance information were both added to one of the plurality of sets, namely a first set, a detailed search is performed on said first set.

Search method

A method for creating an index for searching a structured document having a document data-structure stored, in a computer. The method to be performed in the computer for creating an index includes the steps of: analyzing a structured document to extract a document data-structure in the structured document; normalizing the extracted document data-structure to create a logical structure index composed of a plurality of elements having a hierarchical structure; extracting an appearance number of each element in the created logical structure index; and extracting elements for creating the index, based on the logical structure index, by comparing the extracted element appearance number and a first predetermined threshold.

Method, system and program for creating an index

In registering operation of a document to be searched for, a document identifier management table for managing a range of a document identifier stored for each page and a page identifier of the page is created, and an individual-search-server's search range management table for managing the range of the document identifier in charge of each search server is created. In searching operation of each search server of the document to be searched for, the individual-search-server's search range management table is referred to acquire a range of the allocated document identifier. For each index key forming a query term specified as a query condition, the document identifier management table is referred to to acquire the page identifier storing the document identifier of the allocated range. The searching operation is carried out by referring to a page shown by the acquired page identifier.

System and method to enable parallel text search using in-charge index ranges

Information that individual elements (characteristic character strings) indicative of characteristics of a registered document appear in the registered document is stored in advance. When calculating similarity of the registered document, a query designated by a searcher is analyzed. The query is represented by a characteristic vector having the individual elements which take the relation between a plurality of words into consideration. Pieces of appearance information of the individual words contained in the query are counted. The counted appearance information is compared with a searching index to calculate similarity between documents.

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Tokyo, Japan

Michio Iijima