First we recap the definition of the probability of a particular parse x i,q given parameter settingsā a: Pðx i,q j s i ,ā aÞ ¼ e Fðx i,q ,ā aÞ P j¼1 n i e Fðx i,j ,ā aÞ Recall that the log-loss is Unfortunately, unlike the case of ExpLoss, in general an analytic solution for BestWt does not exist.
we can define an iterative solution using techniques from iterative scaling (Della Pietra, Della Pietra, and Lafferty 1997).