42. The method of claim 41 , wherein numerically expressing the association as the associated score comprises calculating a plural keyword associated score based on the single keyword associated score, and the plural keyword associated score corresponds to a score calculated by numerically expressing an association between the associated keyword or the extended keyword and the other keywords.
43. The method of claim 42 , wherein numerically expressing the association as the associated score comprises calculating, as the plural keyword associated score, a value calculated by dividing a sum total of single keyword associated scores between the sets of the keyword and the other keywords by an amount of keywords included in the sets of the other keywords.