Using a set of gold derivations, we can train the network so that correct order will receive a high score by Equation 4and incorrect one will receive a low score.
when we merge the candidates of two adjacent spans during BTG-based decoding, the local score in Equation 4is useful in two aspects: (1) for the same merging order, it evaluates how well the two candidates are merged; (2) for the different order, it compares the candidates generated by monotone order and inverted order.