Poor scores for NMT on wmt16 English-Romanian with RNN model


I am looking to build an NMT model using RNN model instead of sophisticated Transformer-based model.

Right now, my config looks like this:

save_data: data/wmt16_ro_en/run/
## Where the vocab(s) will be written
src_vocab: data/wmt16_ro_en/run/vocab.src
tgt_vocab: data/wmt16_ro_en/run/vocab.tgt
overwrite: True

# Corpus opts:
        path_src: data/wmt16_ro_en/train.en
        path_tgt: data/wmt16_ro_en/
        path_src: data/wmt16_ro_en/valid.en
        path_tgt: data/wmt16_ro_en/

# common vocabulary for source and target
# share_vocab: True

#### Filter
src_seq_length: 150
tgt_seq_length: 150

# silently ignore empty lines in the data
skip_empty_level: silent

# maximum vocab size
src_vocab_size: 50000
tgt_vocab_size: 50000

# General opts
save_model: data/wmt16_ro_en/run/model
keep_checkpoint: 50
save_checkpoint_steps: 10000
average_decay: 0.0005
seed: 1234
report_every: 100
train_steps: 100000
valid_steps: 5000

# Batching
world_size: 1
gpu_ranks: [0]
batch_type: "tokens"
batch_size: 4096
valid_batch_size: 256
batch_size_multiple: 1
accum_count: [3]
accum_steps: [0]

# Optimization
model_dtype: "fp32"
optim: "adam"
learning_rate: 2
warmup_steps: 8000
decay_method: "noam"
adam_beta2: 0.998
max_grad_norm: 0
label_smoothing: 0.1
param_init: 0
param_init_glorot: true
normalization: "tokens"

# Model
rnn_size: 512
word_vec_size: 512
layers: 2
encoder_type: brnn
dropout: [0.1]

The score on wmt16 English to Romanian dataset is really low i.e. 11.3.

Can anyone suggest any possible modifications to the above config model so that the scores can be improved? Just to re-iterate, I need to work with RNN model only.

Add more layers

Hi Krishna!

  1. Does this model use whole words? Try to increase the size of data and/or consider using subwording (e.g. BPE).

  2. Regarding:

src_seq_length: 150
tgt_seq_length: 150

If the model works on whole words, 150 is too large for words per segment. Check the average number in your test dataset.

Kind regards,