Findings and Considerations in Active Learning Based Framework for Resource-Poor SMT

Active learning (AL) for resource-poor SMT is an efficient and feasible way to acquire a number of high-quality parallel data to improve translation quality. This paper firstly studies two mainstream sentence selection algorithms that are Geom-phrase and Geom n-gram, and then proposes a sentence perplexity based selection method. Some important findings, such as the impact of sentence length on the AL performance, are observed in the comparison experiments conducted on Chinese-English NIST data. Accordingly, a preprocessing strategy is presented to filter the original monolingual corpus for the purpose of obtaining higher-information sentences. Experimental results on preprocessed data show that the the performance of three selection algorithms is significantly improved compared to the results on the original data.