Neg_Sentiment_Fea is feature measures shallow sentiment of sentences, we manually chose a list NEG_SENTIMENT = {'no ', 'not', 'never', 'little', 'few', 'nobody', 'neither', 'seldom' 'hardly', 'rarely', 'scarcely'} to judge the sentiment, the appearance of word in this list indicating an opposed meaning, if only one word in the list appeared only once in this pair of sentences, we think that this pair of sentences expressing opposite meaning.
in our experiments, we also used plenty of style-related features, we call it "literal-based" features.