The LMU Munich Systems for the WMT21 Unsupervised and Very Low-Resource Translation Task

Jindřich Libovický, Alexander Fraser

WMT 2021

We present our submissions to the WMT21 shared task in Unsupervised
and Very Low Resource machine translation between German and Upper
Sorbian, German and Lower Sorbian, and Russian and Chuvash. Our
low-resource systems (German↔Upper Sorbian, Russian↔Chuvash) are
pre-trained on high-resource pairs of related languages. We fine-tune
those systems using the available authentic parallel data and improve
by iterated back-translation. The unsupervised German↔Lower Sorbian
system is initialized by the best Upper Sorbian system and improved by
iterated back-translation using monolingual data only.