Backtranslation is a way of making use of monolingual corpora in the target language by creating synthetic bitexts. In backtranslation, we train an intermediate target-to-source MT system on the small bitext to translate the monolingual target data to the source language. Backtranslation has various parameters. One is how we generate the backtranslated data; we can run the decoder in greedy inference, or use beam search. Or we can do sampling, or Monte Carlo search. In Monte Carlo decoding, at each search timestep, instead of always generating the word with the highest softmax probability, we roll a weighted die, and use it to choose the next word according to its softmax probability.