For example, given the following hypothesis path, <p al="0-1"> izzat ibrahim </p> <p al="2-2"> receives </p> <p al="3-4"> an economic official </p> <p al="5-6"> in </p> <p al="7-7"> baghdad </p> We find the source phrase containing words [0,1] is first translated into a target phrase "izzat ibrahim", which is followed by the translation from source word 2 to a single target word "receives", etc.. We identify the word alignment within the phrase translation pairs based on IBM model-1 scores.
we get the following source word translation sequence from the above hypothesis (note: source word 5 is translated as NULL): 0 < 1 < 2 < 4 < 3 < 6 < 7 Such decoding sequence determines the translation order between any source word pairs, e.g., word 4 should be translated before word 3, 6 and 7.