<cite>Niehues et al. (2011)</cite> also described an alternative variant of the original BiLM, where words are substituted by their POS tags (Figure 2 .a, shaded part). Also, however, POS information by itself may be insufficiently expressive to separate cor- , it still is a likely sequence. Indeed, the log-probabilities of the two sequences with respect to a 4-gram BiLM model 5 result in a higher probability of −10.25 for the incorrect reordering than for the correct one (−10.39). Since fully lexicalized bilingual tokens suffer from data sparsity and POS-based bilingual tokens are insufficiently expressive, the question is which level of syntactic information strikes the right balance between expressiveness and generality.