A Hybrid Morpheme-Word Representationfor Machine Translation of Morphologically Rich LanguagesThis research was sponsored in part by CSIDM (grant # 200805) and by a National Research Foundation grant entitled “Interactive Media Search” (grant # R-252-000-325-279).
Table 2: Baseline system performance (on the test dataset). Shown are word BLEU and morpheme m-BLEU scores for the w-system and m-system.
['[EMPTY]', '[BOLD] w-system BLEU', '[BOLD] w-system m-BLEU', '[BOLD] m-system BLEU', '[BOLD] m-system m-BLEU']
We further introduce a morpheme-token version of BLEU, which we call m-BLEU: it first segments the system output and the reference translation into morpheme-tokens and then calculates a BLEU score as usual. However, the m-system is outperformed by the w-system on the classic word-token BLEU, which means that it either does not perform as well as the w-system or that word-token BLEU is not capable of measuring the morpheme-level improvements. We return to this question later.