More recently, methods that jointly infer the opinion entity and relation extraction tasks (e.g., using Integer Linear Programming (ILP)) have been introduced (Choi et al., 2006;Yang and Cardie, 2013) and show that the existence of opinion relations provides clues for the identification of opinion entities and vice-versa, and thus results in better performance than a pipelined approach.
the success of these methods depends critically on the availability of opinion lexicons, dependency parsers, named-entity taggers, etc.