6. The method according to claim 5 , wherein the weight is differently applied depending on which word of the parsed input set is changed, or depending on a number of words of the parsed input set are changed.
6. The method according to claim 5 , wherein the weight is differently applied depending on which word of the parsed input set is changed, or depending on a number of words of the parsed input set are changed. 7. The method according to claim 6 , wherein a weight applied to the extended input set generated by changing a certain word of the parsed input set to a hyponym is greater than a weight applied to the extended input set generated by changing the certain word to a synonym, and a weight applied to the extended input set generated by changing the certain word to a hypernym is greater than the weight applied to the extended input set generated by changing the certain word to the hyponym.