| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that a head moving distance on a disc unit gets long to bring lowering of a retrieving speed, when a volume of registered documents gets large. SOLUTION: When the registered document 15 is registered as a document data 12, a document control system prepares in order an N-gram position information block 7 and an N-gram position information block storage position 6 in every in-block document number 4' of a predetermined threshold value or less, in a blocked N-character index 1, and the document control system 14 reads out the N-gram position information block 7 related to an N-gram of a retrieving key word, to a buffer 16, when the key word is given.
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