We describe k-best decoding for our hybrid model and design its loss function and the features appropriate for our task.

Given a training example (xt, yt), MIRA tries to establish a margin between the score of the correct path 3(xt,yt;w) and the score of the best candidate path 3(xt, j}; w) based on the current weight vector w that is proportional to a loss function L(yt, 37).

4.3 Loss function

We instead compute the loss function through false positives (FF) and false negatives (FN).

In this paper, we have described how MERT can be employed to estimate the weights for the linear loss function to maximize BLEU on a development set.

Note that N -best MBR uses a sentence BLEU loss function .

This reranking can be done for any sentence-level loss function such as BLEU (Papineni et al., 2001), Word Error Rate, or Position-independent Error Rate.

They use the following loss function , of which a linear approximation to BLEU (Papineni et al., 2001) is a special case,

With the above loss function , Tromble et al.

15 The MBR becomes the MAP decision rule of (1) if a so-called zero-one loss function is used: l(y, y’) = 0 if y = y’ ; otherwise l(y,y’) = 1.