The language model was a trigram model with modified Kneser-Ney smoothing (Kneser and Ney, 1995;Chen and Goodman, 1998), trained on the target  Table 2: Forest-to-string translation outperforms tree-tostring translation according to Bleu, but the decreases parsing accuracy according to labeled-bracket F1.
when we train to maximize labeled-bracket F1, forest-to-string translation yields better parses than both tree-to-string translation and the original parser.