6. The method of claim 2 , wherein if the document segment is a sentence, the correlation degree between this sentence and its neighboring sentence is determined based on the correlation degrees between the words in this sentence and the words in its neighboring sentence.
6. The method of claim 2 , wherein if the document segment is a sentence, the correlation degree between this sentence and its neighboring sentence is determined based on the correlation degrees between the words in this sentence and the words in its neighboring sentence. 9. The method of claim 6 , wherein the correlation degree between two words is determined based on statistics using a large corpus.