Note that state-ofthe-art pronoun resolvers (e.g., JavaRAP (Qiu et al., 2004), GuiTaR (Poesio and Kabadjov, 2004), as well as those designed by Mitkov (2002) and Charniak and Elsner (2009)) and coreference resolvers (e.g., BART (Versley et al., 2008), CherryPicker (Rahman and Ng, 2009), Reconcile (Stoyanov et al., 2010), the Stanford resolver (Raghunathan et al., 2010;Lee et al., 2011)) cannot accurately resolve the difficult pronouns in these structurally simple sentences, as they do not have the mechanism to capture the fine distinctions between twin sentences.
when given these sentences, the best that the existing resolvers can do to resolve the pronouns is guessing.