The word sequence was converted to a phrase sequence as follows, by applying rules which combine two adjacent words: ,--,.,:,POS,-RRB-,-RSB-,-RCB-} P P ≡ {IN,RP,TO,DT,PDT,PRP,WDT,WP,WP$,WRB} N N ≡ {CD,FW,NN,NNP,NNPS,NNS,SYM,JJ} do  then Combine the words vi and vi+1 until No rules are applied We constructed a Japanese polarity reversing word dictionary from the Automatically Constructed Polarity-tagged corpus (Kaji and Kitsuregawa, 2006).
in sentiment classification, a sentence which contains positive (or negative) polarity words does not necessarily have the same polarity as a whole, and we need to consider interactions between words instead of handling words independently.