8. The system of claim 1 , wherein a plurality of converted character strings are generated by appending a plurality of characters corresponding to a plurality of inflectional forms thereto, where at least one character is appended to each inflectional form, with respect to the target character string of an inflectional word.
8. The system of claim 1 , wherein a plurality of converted character strings are generated by appending a plurality of characters corresponding to a plurality of inflectional forms thereto, where at least one character is appended to each inflectional form, with respect to the target character string of an inflectional word. 9. The system of claim 8 , wherein the retrieval condition of matching the target character string and not matching the converted character string is generated based on the converted character string not having the attribute, and wherein the operations performed by the processor further include: determining whether the converted character string has the attribute based on the target character string that is based on a frequency at which the converted character string matches the third text with which the attribute is associated.