More sophisticated features based on different kinds of similarity measures have also been considered, such as the surface similarity based on Dice coefficient and the WuPalmer WordNet similarity between argument heads (Mc-Conky et al., 2012;Cybulska and Vossen, 2013;Krause et al., 2016).
these features are computed using either the outputs of event argument extractors and entity coreference resolvers (Ahn, 2006;Ng, 2014, 2015; or semantic parsers (Bejan and Harabagiu, 2014;Yang et al., 2015;Peng et al., 2016) and therefore suffer from serious error propagation issues (see Lu and Ng (2018)).