Positional Encoding to Control Output Sequence Length
Table 3: Recall-oriented ROUGE scores in DUC-2004.
['Model', 'R-1', 'R-2', 'R-L']
Following the evaluation protocol Over et al. The table indicates that LDPE and LRPE significantly improved the performance compared to the bare Transformer, and achieved better performance than the baselines except for R-2 of LenInit. This table also shows the scores reported in the previous studies. The proposed method outperformed the previous methods that control the output length and achieved the competitive score to the state-of-the-art scores. Since the proposed method consists of a character-based decoder, it sometimes generated words unrelated to a source sentence. Thus, we applied a simple re-ranking to each n-best headlines generated by the proposed method (n=20 in this experiment) based on the contained words. Our re-ranking strategy selects a headline that contains source-side words the most.