For this, we compute event chains, which are defined as sequences of events that share the same actor or object, in subject or direct object role (Chambers and Jurafsky, 2008).
we encode the following additional features in the Events feature set: (4) the length of the longest chain found in the essay (i.e., number of event pairs in the chain); (5) the score of the longest chain (computed as the sum of PMI values for all links (event pairs) of the chain); (6) the length of the second longest chain found in the essay; (7) the score of the highest scoring chain in the essay; (8) the score of the second highest scoring chain in the essay; (9) the score of the lowest scoring chain is the essay; (10) the sum of scores for all chains in the essay.