| 摘要 |
PROBLEM TO BE SOLVED: To efficiently and quickly perform retrieval from a compressed block string by substituting partial character strings constituting a digitized text with compressed blocks in a retrieval device which determines whether the text includes a prescribed character string described using regular expressions or not and obtains its position. SOLUTION: A DFA (deterministic finite automaton) is utilized for retrieval. A compressed block (code) is acquired from the compressed block string (code string) (S21). In the case that a partial character string corresponding to the compressed block is new, the compressed block is decompressed into the partial character string and is inputted to the DFA, and the history of state transition (state history) of the DFA at this time is stored (S261 to S264). Compressed blocks corresponding to the same partial character string are not decompressed, and the state history is referred to update the state of the DFA (S251 to S254). COPYRIGHT: (C)2007,JPO&INPIT
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