Corpus-based approaches (contd)
(Kanayama and Nasukawa, EMNLP-06) takes a similar approach to (Hazivassiloglou and McKeown, ACL-97) but for Japanese words:
Instead of using learning, it uses two criteria to determine whether to add a word to positive or negative lexicon.
Have an initial seed lexicon of positive and negative words.
(Ding and Liu, 2007) also exploits constraints on connectives, but with two differences
It uses them to assign opinion orientations to product features (more on this later).
One word may indicate different opinions in the same domain.
“The battery life is long” (+) and “It takes a long time to focus” (-).
Find domain opinion words is insufficient.
It can be used without a large corpus.