Patent ID: 7103536

Claim:
A method of compiling a machine-retrievable symbol dictionary for symbol data registering a finite number of symbols mutually different out of an array of not more than N (a specific number of) characters contained in a certain predetermined character set, comprising: a first step of compiling said symbol dictionary wherein (a) a symbol covering means retrieves each symbol of said symbol data from a prepared meta-symbol dictionary in an initial state and searches for a covering being a set of a pair of a meta-symbol and a start character position for collating with a partial character string in the symbols to be covered having one or more extension meta-symbol pairs for each character and produces a covering result, (b) a meta-symbol accumulating means sums up said covering results, where a total appearance frequency of occurrence of each meta-symbol in said symbol data is accumulated in a meta-symbol frequency table, (c) a meta-symbol dictionary update judging means refers to the meta-symbol frequency table and after deleting a first meta-symbol from said meta-symbol dictionary according to a first predetermined condition, adds a second meta-symbol to said meta-symbol dictionary according to a second predetermined condition, a second step of compiling said symbol dictionary in which (d) the symbol covering means retrieves each symbol in said symbol data in said meta-symbol dictionary to search for the covering and produces a further covering result, (e) the meta-symbol summing means sums up the covering results, (f) the total appearance frequency in said symbol data in each meta-symbol is accumulated in the meta-symbol frequency table, (g) said meta-symbol dictionary update judging means refers to said meta-symbol frequency table, adds meta-symbols to said meta-symbol dictionary according to the first predetermined condition, judges if a predetermined stopping condition is satisfied or not, and repeats the second step until satisfying the stopping condition, a third step of compiling said symbol dictionary in which said meta-symbol dictionary update judging means refers to the meta-symbol frequency table, and deletes meta-symbols from said meta-symbol dictionary according to said second predetermined condition, a fourth step of compiling said symbol dictionary in which said symbol covering means covers said symbol data by using said meta-symbol dictionary compiled at the third step, and a meta-symbol appearance information compiling means calculates the meta-symbol appearance information recording a symbol number for containing each meta-symbol and the appearance character position from the covering result for each meta-symbol, and a fifth step of compiling said symbol dictionary in which the symbol dictionary compiling means compiles a machine-retrievable symbol dictionary storing meta-symbol information and meta-symbol appearance information from said meta-symbol dictionary and meta-symbol appearance information.