The richer representation allows for a finer distinction between reorderings. For example, Arabic has a morphological marker of definiteness on both nouns and adjectives. If we first translate a definite adjective and then an indefinite noun, it will probably not be a likely sequence according to the translation model. This kind of intuition underlies the model of <cite>Niehues et al. (2011)</cite> , a bilingual LM (BiLM), which defines elementary translation events t 1 , ..., t n as follows: where e i is the i-th target word and A : E → P(F ) is an alignment function, E and F referring to target and source sentences, and P(·) is the powerset function. In other words, the i-th translation event consists of the i-th target word and all source words aligned to it.