But this approach usually introduces many irrelevant mentions, and it's very difficult to automatically determine the scope of discourse.
some recent work exploited more restricted measures by only choosing those mentions which are topically related (Cassidy et al., 2012;Xu et al., 2012), bear a relation from a fixed set (Cheng and Roth, 2013), coreferential (Nguyen et al., 2012;Huang et al., 2014), socially related (Cassidy et al., 2012;Huang et al., 2014), dependent (Ling et al., 2014), or a combination of these through meta-paths (Huang et al., 2014).