6 To avoid overfitting the exact definition of KL cpos 3 and KL −4 cpos 3 to the 30 treebanks, we used only 12 4 The KL divergence is non-symmetric; DKL(P ||Q) expresses the amount of information lost when a distribution Q is used to approximate the true distribution P .
in our setting, we use DKL(tgt||src), as we try to minimize the loss of using a src parser as an approximation of a tgt parser.