The most basic word alignment model, IBM model 1, can be described using the following generative process (Brown et al., 1993): Given an English sentence E = e 1 , ..., e l , first choose a length m for the foreign sentence F .
we place the following assumptions on IBM model 1: In this probability modelling we assume that the alignment positions are determined using the uniform distribution, and that word translations are generated depending on the source word -the probability of translating to a specific foreign word depends on the observed frequency of pairs of the foreign word and the given source word.