The scoring function of MMR con-Algorithm 1: MMR-BS Decoding Input: the user-issued query q, the max length of reply l, λ in MMR function Output: generated reply set R R = ∅; S 0 = ∅; for t = 1; t ≤ l; do // obtain the subsequence set at time i S t = Decoding(q, S t−1 ); // coarse-grained selection siders the quality of a candidate as well as its diversity against previously selected ones.
we have two metrics: sim qua (s i , q) measures the similarity of a candidate subsequence s i with respect to the query q, indicating the quality of s i .