Therefore, the objective of our search algorithm is defined as score(f , e, a, w, θ) = M (f , e, a, θ) + λC(f , e, a, w) where M (f , e, a, θ) is alignment model score, θ is a set of model parameters, C(f , e, a, w) is coverage (either hard or soft), and λ is a hyperparameter that controls the preference between alignment model score and coverage.
2 the decision rule is given bŷ a = argmax a∈A(f ,e) score(f , e, a, w, θ) where A(f , e) is a set of all possible alignments for the sentence pair.