How rule-based and statistical machine translation can help each other

Here are a few suggestions on how rule-based and statistical machine translation  can help each other:

(This is a follow-up to the previous post)

  • to begin with, rule-based and statistical machine translation are often contrasted and compared: it would be oversimplifying to conclude that one is better than the other. From a more objective standpoint, let us consider that each method has its strengths and weaknesses. Let us investigate on how one could make them collaborate in order to add up their respective strengths
  • in the case of an endangered language, the lack of good quality corpora has been pointed out. But one way for rule-based and statistical machine translation to collaborate would be to use rule-based translation for building a better quality corpus for statistical machine translation
  • suppose we begin with a statistical machine translation software that performs 50% on average with regard to French to Corsican translation
  • let us sketch the process of creating these better corpora: let us take the example of the French-Corsican diglossic pair (the Corsican language being considered by Unesco as a definitely endangered language). Now presently we lack a quality French-Corsican corpus or to say it more accurately, the corpus at our disposal is a low-quality one. The idea would be to use rule-based machine translation to create a much better corpus to use with statistical machine translation.
  • let us sketch now the different steps of this collaborative process: (i) create a French-Corsican corpus with the help of rule-based machine translation: if the software has some average 90% performance, then the corpus would be on average 90% reliable. With appropriate training, statistical MT should now perform some, say, 80% on average (to be compared with the previous 50% performance)
    (ii) from this French-Corsican corpus, other corpora pairs can be created, such as Italian-Corsican, English-Corsican, etc. since French-Italian, English-Italian, etc. corpora of excellent quality already exist. The performance gain should then extend to other language pairs such as Italian-Corsican, English-Corsican, etc.
  • with the help of this process, we re finally in a position to combine and add up the strengths of the two complementary approaches to MT: on the one hand, rule-based MT is able to translate with good accuracy even in the lack of corpora; on the other hand, statistical machine translation is able to handle successfully and fastly a great many language pairs. To sum up, as the Corsican proverb says: una mani lava l’altra (One hand washes the other).
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