13. An information abstracting apparatus comprising: input means for accepting an input of character string data divided into prescribed units each subdivided into prescribed paragraphs, with each individual character represented by a character code; keyword extracting means for extracting a keyword for each paragraph in each of said prescribed units from said character string data input from said input means; keyword associating means for generating a keyword association by associating one keyword with another among keywords obtained from the same paragraph; similarity calculating means for calculating similarity between keywords thus extracted, on the basis of a plurality of factors including said keyword association; weighting means for weighting said extracted keyword by taking into account a state of occurrence, in the other prescribed units, of keywords that are identical or similar to said extracted keyword, and for weighting said generated keyword association by taking into account a state of occurrence, in the other prescribed paragraphs, of keyword associations that are identical to said generated keyword association; selecting means for selecting keywords and keyword associations from said extracted keywords and said generated keyword associations on the basis of the weighted results; and outputting said selected keywords and keyword associations as an information abstract relating to said character string data.
13. An information abstracting apparatus comprising: input means for accepting an input of character string data divided into prescribed units each subdivided into prescribed paragraphs, with each individual character represented by a character code; keyword extracting means for extracting a keyword for each paragraph in each of said prescribed units from said character string data input from said input means; keyword associating means for generating a keyword association by associating one keyword with another among keywords obtained from the same paragraph; similarity calculating means for calculating similarity between keywords thus extracted, on the basis of a plurality of factors including said keyword association; weighting means for weighting said extracted keyword by taking into account a state of occurrence, in the other prescribed units, of keywords that are identical or similar to said extracted keyword, and for weighting said generated keyword association by taking into account a state of occurrence, in the other prescribed paragraphs, of keyword associations that are identical to said generated keyword association; selecting means for selecting keywords and keyword associations from said extracted keywords and said generated keyword associations on the basis of the weighted results; and outputting said selected keywords and keyword associations as an information abstract relating to said character string data. 14. An information abstracting apparatus according to claim 13, wherein the larger the number of paragraphs containing said keyword association constituted by the keywords having said larger similarity between the keywords is, the larger the weight which is to be assinged to the keyword association becomes.