Most existing works on sentiment summarization focus on predicting the overall rating on an entity (Pang et al., 2002;Pang and Lee, 2004) or estimating ratings for product features (Lu et al., 2009;Lerman et al., 2009;Snyder and Barzilay, 2007;Titov and McDonald, 2008)).
the opinion summaries in such systems are extractive, meaning that they generate a summary by concatenating extracts that are representative of opinion on the entity or its aspects.