Context dependent opinions
Popescu and Etzioni (EMNLP-05) used
constraints of connectives in (Hazivassiloglou and McKeown, ACL-97), and some additional constraints, e.g., morphological relationships, synonymy and antonymy, and
relaxation labeling to propagate opinion orientations to words and features.
Ding and Liu (2008) used
constraints of connectives both at intra-sentence and inter-sentence levels, and
additional constraints of, e.g., TOO, BUT, NEGATION, ….
to directly assign opinions to (f, s) with good results (> 0.85 of F-score).