XMEANT: Better semantic MT evaluation without reference translations

Chi-kiu Lo, Meriem Beloucif, Markus Saers, Dekai Wu

Abstract: We introduce XMEANT—a new cross-lingual version of the semantic frame based MT evaluation metric MEANT—which can correlate even more closely with human adequacy judgments than monolingual MEANT and eliminates the need for expensive human references. Previous work established that MEANT reflects translation adequacy with state-of-the-art accuracy, and optimizing MT systems against MEANT robustly improves translation quality. However, to go beyond tuning weights in the loglinear SMT model, a cross-lingual objective function that can deeply integrate semantic frame criteria into the MT training pipeline is needed. We show that cross-lingual XMEANT outperforms monolingual MEANT by (1) replacing the monolingual context vector model in MEANT with simple translation probabilities, and (2) incorporating bracketing ITG constraints.