The zero anaphora resolution is one of the active research areas in the Japanese language processing as it is crucial for improving the performance of various natural language processing applications such as automatic text summarisation (Yamada et al., 2017), information extraction (Sudo et al., 2001) and machine translation (Kudo et al., 2014).
it has been extensively studied as an urgent problem to be solved (Sasano and Kurohashi, 2011;Hangyo et al., 2013;Ouchi et al., 2017;Matsubayashi and Inui, 2017).