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# FSMT

## Overview

FSMT (FairSeq MachineTranslation) models were introduced in [Facebook FAIR's WMT19 News Translation Task Submission](https://arxiv.org/abs/1907.06616) by Nathan Ng, Kyra Yee, Alexei Baevski, Myle Ott, Michael Auli, Sergey Edunov.

The abstract of the paper is the following:

*This paper describes Facebook FAIR's submission to the WMT19 shared news translation task. We participate in two
language pairs and four language directions, English <-> German and English <-> Russian. Following our submission from
last year, our baseline systems are large BPE-based transformer models trained with the Fairseq sequence modeling
toolkit which rely on sampled back-translations. This year we experiment with different bitext data filtering schemes,
as well as with adding filtered back-translated data. We also ensemble and fine-tune our models on domain-specific
data, then decode using noisy channel model reranking. Our submissions are ranked first in all four directions of the
human evaluation campaign. On En->De, our system significantly outperforms other systems as well as human translations.
This system improves upon our WMT'18 submission by 4.5 BLEU points.*

This model was contributed by [stas](https://huggingface.co/stas). The original code can be found
[here](https://github.com/pytorch/fairseq/tree/master/examples/wmt19).

## Implementation Notes

- FSMT uses source and target vocabulary pairs that aren't combined into one. It doesn't share embeddings tokens
  either. Its tokenizer is very similar to [`XLMTokenizer`] and the main model is derived from
  [`BartModel`].


## FSMTConfig

[[autodoc]] FSMTConfig

## FSMTTokenizer

[[autodoc]] FSMTTokenizer
    - build_inputs_with_special_tokens
    - get_special_tokens_mask
    - create_token_type_ids_from_sequences
    - save_vocabulary

## FSMTModel

[[autodoc]] FSMTModel
    - forward

## FSMTForConditionalGeneration

[[autodoc]] FSMTForConditionalGeneration
    - forward