Constrained APE

A fork from fairseq. Please see Fairseq how to install.

Things added

• fairseq/data/ape_dataset.py: based on LanguagePairDataset. Added support for mt, term, and others
• fairseq/data/ape_lev.py: based on trans_lev. Added support for custom initialization for prev_target for training and init_tokens at test time
  • Parameters:
  • --input-type: input to be fed into the encoder. Choices are src-only, concatenate, and multisource. Concatenate combines src and mt with , and multisource will change the input into a dictionary of src and mt (required by MultisourceEncoder).
  • --prev-target: initialization for prev_target for imitation learning. Choices are target, mt, and term.
  • --init-output: Initialization of starting string at test time. Choices are blank, mt, and term.
• fairseq/models/multisource_encoder.py: Encoder similiar to CompositeEncoder, but takes in separate input for each encoder and concatenate the outputs of all encoders before passing into the decoder.
• fairseq/models/nat/multisource_levenshtein_transformer.py: LevenshteinTransformer with MultisourceEncoder
  • Parameters:
  • --share-encoder: Using the same encoder for src_encoder and mt_encoder
• fairseq/models/multisource_transformer.py: Transformer with MultisourceEncoder
  • Parameters:
  • --share-encoder: Using the same encoder for src_encoder and mt_encoder

Dataset creation

1. Download the APE dataset from the official WMT website (PBMT, NMT). Artifical dataset and eSCAPE can be downloaded there as well
2. Using Moses, learn and apply truecasing, and tokenize
3. Learn BPE with subword-nmt and apply to the dataset
4. Binarize the files using Fairseq's preprocess command. The directory should contain files with the following suffixes: src, mt, pe for the standard APE task. For terminologies, files with the names term, src_append, src_append_embed, src_replace, src_replace_embed are expected

Terminology Dataset

1. Extract English Wiktionary using WikiExtractor
2. Use $FILE$ to extract terminology pair
3. Alternatively, our terminonology is provided in the directory terms. Each file is separated by tabs. For each line, if a terminology match is found, each terminology pair consists of four entries (source word, source word index, target word, target word index).

Examples to run the Models

Levenshtein Transformer training from noisy_mt -> target

fairseq-train \
    $TRAIN_DIR \
    --save-dir checkpoints/levenshtein_transformer_mt_prev_target \
    --ddp-backend=no_c10d \
    --task ape_lev \
    --criterion nat_loss \
    --arch levenshtein_transformer \
    --noise random_delete \
    --share-all-embeddings \
    --optimizer adam --adam-betas '(0.9,0.98)' \
    --lr 0.0005 --lr-scheduler inverse_sqrt \
    --min-lr '1e-09' --warmup-updates 10000 \
    --warmup-init-lr '1e-07' --label-smoothing 0.1 \
    --dropout 0.3 --weight-decay 0.01 \
    --decoder-learned-pos \
    --encoder-learned-pos \
    --apply-bert-init \
    --fixed-validation-seed 7 \
    --max-tokens 8000 --update-freq 8 \
    --save-interval-updates 10000 --no-epoch-checkpoints \
    --max-update 300000 --source-lang src --target-lang pe --fp16 \
    --num-workers 16 --prev-target mt\

Multisource Levenshtein Transformer

fairseq-train \
    $TRAIN_DIR \
    --save-dir checkpoints/multisource_levenshtein_transformer \
    --ddp-backend=no_c10d \
    --task ape_lev \
    --criterion nat_loss \
    --arch multisource_levenshtein_transformer \
    --noise random_delete \
    --share-all-embeddings \
    --optimizer adam --adam-betas '(0.9,0.98)' \
    --lr 0.0005 --lr-scheduler inverse_sqrt \
    --min-lr '1e-09' --warmup-updates 10000 \
    --warmup-init-lr '1e-07' --label-smoothing 0.1 \
    --dropout 0.3 --weight-decay 0.01 \
    --decoder-learned-pos \
    --encoder-learned-pos \
    --apply-bert-init \
    --fixed-validation-seed 7 \
    --max-tokens 8000 --update-freq 8 \
    --save-interval-updates 10000 --no-epoch-checkpoints \
    --max-update 300000 --source-lang src --target-lang pe --fp16 \
    --num-workers 16 --input-type multisource

Multisource Transformer

fairseq-train \
    $TRAIN_DIR \
    --save-dir checkpoints/multisource_transformer \
    --arch multisource_transformer --share-decoder-input-output-embed \
    --task ape \
    --optimizer adam --adam-betas '(0.9, 0.98)' --clip-norm 0.0 \
    --lr 5e-4 --lr-scheduler inverse_sqrt --warmup-updates 4000 \
    --dropout 0.3 --weight-decay 0.0001 \
    --criterion label_smoothed_cross_entropy --label-smoothing 0.1 \
    --max-tokens 8000 --update-freq 8 \
    --save-interval-updates 10000 --no-epoch-checkpoints \
    --max-update 300000 --source-lang src --target-lang pe --fp16 \
    --num-workers 16 --input-type multisource