As a result, we will modify our objective function of (4) to take yet another expectation over the unknown y.
we will replace L(δ Now, the minimum imputed empirical risk objective of (4) becomes If the loss function L(y, y i ) is a negated BLEU, this is equivalent to performing minimum-risk training described by (Smith and Eisner, 2006;Li and Eisner, 2009) on the imputed data.