5.3 Sentiment Lexicon Induction

(2007) propose two methods for translating sentiment lexicons .

The first method simply uses bilingual dictionaries to translate an English sentiment lexicon .

The induction of a sentiment lexicon is the subject of early work by (Hatzivassiloglou and McKeown, 1997).

where O is the set of terms in the sentiment lexicon , P(sub|w) indicates the probability of term 212 being subjective, and n(w, D) is the number of times term 21) occurs in document D. The opinion scoring can weigh lexicon terms differently, using P(sub|w); it normalizes scores to cancel out the effect of varying document sizes.

where n(O, D) is the number of matches of the term of sentiment lexicon O in document D.

Since it is unrealistic to construct sentiment lexicons , or manually annotate text for learning, for every imaginable domain or topic, automatic methods have been developed.

Sentiments are extracted using a sentiment lexicon and pattern matched from dependency trees of sentences.

Note that since our method relies on only sentiment lexicon , extractable aspects are unlimited.

1Since we aim to summarize Japanese reviews, we utilize Japanese sentiment lexicon (Asano et al., 2008).