6. The document clustering system according to claim 1 , wherein the superconcept setting unit references to the document set and selects words around the two words, references to the co-occurring pattern and compares that with the co-occurring pattern of the higher-order words of the surrounding words, and selects the context conforming higher-order words by finding the average of the degree of coinciding co-occurrence.
6. The document clustering system according to claim 1 , wherein the superconcept setting unit references to the document set and selects words around the two words, references to the co-occurring pattern and compares that with the co-occurring pattern of the higher-order words of the surrounding words, and selects the context conforming higher-order words by finding the average of the degree of coinciding co-occurrence. 15. The document clustering system according to claim 6 , wherein the superconcept setting unit finds higher-order words of the surrounding words based on the amount of mutual information based on the frequency of appearance of co-occurring words.