First, we start with the intuition that the assumption of symmetry strengthens the confidence of a translation pair.
if the most probable translation candidate for a source word w S 1 is a target word w T 2 and, vice versa, the most probable translation candidate of the target word w T 2 is the source word w S 1 , and their TI+Cue scores are above a certain threshold, we can claim that the words w S 1 and w T 2 are a translation pair.