(2017) which rewards n-grams from syntactic translation lattices during NMT decoding, we add an additional reward for n-grams that occur in the collected translation pieces.
as shown in Figure 2, at each time step t, we update the probabilities over the output vocabulary and increase the probabilities of those that result in matched n-grams according to where λ can be tuned on the development set and δ (•) is computed as Equation 8 if y t t−n+1 ∈ G X , otherwise δ (•) = 0.