With this notation, the score for a coreference out- is the product of individual scores assigned to the corresponding action sequence {a i } n i=1 , and the best coreference result is the one with the highest score:Ê Given n mentions, the number of all possible entity outcomes is the Bell Number (Bell, 1934): Exhaustive search is out of the question.
we organize hypotheses into a Bell Tree (Luo et al., 2004) and use a beam search with the following pruning strategy: first, a maximum beam size (typically 20) S is set, and we keep only the top S hypotheses; Second, a relative threshold r (we use 10 −5 ) is set to prune any hypothesis whose score divided by the maximum score falls below the threshold.