Ternary segmentation for improving search in top-down induction of segmental ITGs

We show that there are situations where iteratively segmenting sentence pairs top-down will fail to reach valid segments and propose a method for alleviating the problem. Due to the enormity of the search space, error analysis has indicated that it is often impossible to get to a desired embedded segment purely through binary segmentation that divides existing segmental rules in half – the strategy typically employed by existing search strategies – as it requires two steps. We propose a new method to hypothesize ternary segmentations in a single step, making the embedded segments immediately discoverable.