Neural Polysynthetic Language Modelling
Table 4.3: Results of Inuktitut-to-English NMT systems as evaluated by BLEU, chrF, YiSi-0 and YiSi-1 .
['iku segmentation', 'eng segmentation', 'BLEU', 'chrF', 'YiSi-0', 'YiSi-1']
We compared BPE of various vocabulary sizes to the morphological analysis described above. We think this is not due to a problem in the morphological analysis itself (e.g. identifying morphemes incorrectly), but that the process left unanalyzable words intact, whereas BPE manages to segment all words into more manageable pieces. We therefore also performed a preliminary attempt to combine them, in hopes of combining some of the benefits of true morphological analysis with the statistical advantages of BPE. Manual inspection of the results of this process suggest that morphemes identified in morphological analysis were typically left intact by BPE – that is to say, they were identified as units by BPE as well – and only unanalyzed words were further segmented.