July 30, 2011

RegMT System for Machine Translation, System Combination, and Evaluation

Ergun Bicici; Deniz Yuret. Proceedings of the Sixth Workshop on Statistical Machine Translation. pp. 323-329. Edinburgh, Scotland. July, 2011. (PDF, BIB, Proceedings, Poster)

Abstract: We present the results we obtain using our RegMT system, which uses transductive regression techniques to learn mappings between source and target features of given parallel corpora and use these mappings to generate machine translation outputs. Our training instance selection methods perform feature decay for proper selection of training instances, which plays an important role to learn correct feature mappings. RegMT uses L2 regularized regression as well as L1 regularized regression for sparse regression estimation of target features. We present translation results using our training instance selection methods, translation results using graph decoding, system combination results with RegMT, and performance evaluation with the
F1 measure over target features as a metric for evaluating translation quality.

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Instance Selection for Machine Translation using Feature Decay Algorithms

Ergun Bicici; Deniz Yuret. Proceedings of the Sixth Workshop on Statistical Machine Translation. pp. 272-283. Edinburgh, Scotland. July, 2011. (PDF, BIB, Proceedings, Presentation)

Abstract: We present an empirical study of instance selection techniques for machine translation. In an active learning setting, instance selection minimizes the human effort by identifying the most informative sentences for translation. In a transductive learning setting, selection of training instances relevant to the test set improves the final translation quality. After reviewing the state of the art in the field, we generalize the main ideas in a class of instance selection algorithms that use feature decay. Feature decay algorithms increase diversity of the training set by devaluing features that are already included. We show that the feature decay rate has a very strong effect on the final translation quality whereas the initial feature values, inclusion of higher order features, or sentence length normalizations do not. We evaluate the best instance selection methods using a standard Moses baseline using the whole 1.6 million sentence English-German section of the Europarl corpus. We show that selecting the best 3000 training sentences for a specific test sentence is sufficient to obtain a score within 1 BLEU of the baseline, using 5% of the training data is sufficient to exceed the baseline, and a ~ 2 BLEU improvement over the baseline is possible by optimally selected subset of the training data. In out-of-domain translation, we are able to reduce the training set size to about 7% and achieve a similar performance with the baseline.

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