While this relation between causal and coreference relations is strictly true for gold standard data, we observed that these constraints make the system very sensitive to noise when using system predicted coreference links.
we added binary leakage variables c 1 (i, j, k), c 2 (i, j, k) and c 3 (i, j) to relax these constraints.By maximizing the negative of leakage variables, we allow our model to overcome this instability.