Extracting Opinion Propositions And Opinion Holders Using Syntactic And Lexical Cues

A new task is identified in the ongoing analysis of opinions: finding propositional opinions, sentential complement clauses of verbs such as "believe" or "claim" that express opinions, and the holders of these opinions. An extension of semantic parsing techniques is proposed that, coupled with additional lexical and syntactic features, can extract these propositional opinions and their opinion holders. A small corpus of 5,139 sentences is annotated with propositional opinion information, and is used for training and evaluation. While our results are still quite preliminary (precisions of 43-51% and recalls of 58-68%), we feel that our focus on opinion clauses, and in general the use of rich syntactic features, helps point to an important new direction in opinion detection.