Fuzzy matching for N-gram-based MT evaluation

  • Authors:
  • Liangyou Li;Zhengxian Gong

  • Affiliations:
  • School of Computer Science & Technology, Soochow University, Suzhou, Jiangsu, China;School of Computer Science & Technology, Soochow University, Suzhou, Jiangsu, China

  • Venue:
  • CLSW'12 Proceedings of the 13th Chinese conference on Chinese Lexical Semantics
  • Year:
  • 2012

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Abstract

N-gram-based metrics have been used widely in automatic evaluation of machine translation. However, most of them also lose merits due to the strict policy of matching of n-grams. Especially, the policy of exact matching leads to take synonyms as totally different words and thus give unreasonable estimation. This paper introduces fuzzy matching for n-grams, which refers to a semantic similarity function based on WordNet. And it is used to find a match with the highest similarity when incorporated into BLEU, the representative of n-gram-based evaluation metrics. Since WordNet can contribute more to high-order n-grams and fuzzy matching can perform well even with fewer references, experiments on MTC Part 2 (LDC2003T17) show our proposed method can greatly improve correlation between BLEU and human evaluation both at segment-level and document-level. Furthermore, BLEU incorporating fuzzy matching achieves more significant improvement at document-level evaluation.