Recall assumption (2), in order to incorporate lexical, structural and semantic information for the similarity calculation of two SSRs holding the same discourse relation, three types of matches were defined for  Intuitively, a simple way of estimating the similarity between two SSRs was using the number of mismatches.
we utilized match( where i ̸ = j, which integrated the three types of matches defined above to calculate the number of mismatches and generate common SSRs.