Later, unified models are proposed to conduct sentence selection and redundancy control simultaneously (McDonald, 2007;Filatova and Hatzivassiloglou, 2004;Yih et al., 2007;Gillick et al., 2007;Lin and Bilmes, 2010;Lin and Bilmes, 2012;Sipos et al., 2012).
extraction-based approaches are unable to evaluate the salience and control the redundancy on the granularity finer than sentences.