The Helsinki Neural Machine Translation System\ThanksThe software is available from https://github.com/robertostling/hnmt under the GNU General Public License version 3.
Table 2: Development results with different segmentation strategies for the source language encoder and the target language decoder and different proportions of backtranslated and parallel data (None = 2.5M sentences of parallel data + 0 sentences of backtranslated data; Only = 0 + 5.5M; Balanced = 2.5M + 2.5M; All = 2.5M + 5.5M).
['Encoder', 'Decoder', 'BLEU None', 'BLEU Only', 'BLEU Balanced', 'BLEU All', 'chrF3 None', 'chrF3 Only', 'chrF3 Balanced', 'chrF3 All']
In preliminary experiments, we focused on different segmentation strategies for the source and target sides as well as on different proportions of backtranslations and parallel data. The models were evaluated on newsdev2015 using lowercased BLEU and chrF3.