StructuralKD

The code is for our ACL-IJCNLP 2021 paper: Structural Knowledge Distillation: Tractably Distilling Information for Structured Predictor

StructuralKD is a framework for training stronger and smaller models through knowledge distillation (KD). StructuralKD can exactly calculate the KL divergence between different output structures between teacher and student models.

Guide

• Requirements
• Datasets
• Scenarios
  • Teacher and Student Share the Same Factorization Form
    • Linear-Chain CRF⇒Linear-ChainCRF
      • Teacher Models
      • Training Student Models
    • Graph-based Dependency Parsing⇒Dependency Parsing as Sequence Labeling
      • Teacher Models
      • Training Student Models
  • Student Factorization Produces More Fine-grained Substructures than Teacher Factorization
    • Linear-Chain CRF⇒MaxEnt
      • Teacher Models
      • Training Student Models
    • Second-Order Dependency Parsing⇒Dependency Parsing as Sequence Labeling
      • Teacher Models
      • Training Student Models
  • Teacher Factorization Produces More Fine-grained Substructures than Student Factorization
    • MaxEnt⇒Linear-Chain CRF
      • Teacher Model
      • Training Student Models
  • Factorization Forms From Teacher andStudent are Incompatible
    • Coming Soon
• Parse files
• Config File
• Citing Us
• Contact

Requirements

The project is based on PyTorch 1.1+ and Python 3.6+. To run our code, install:

pip install -r requirements.txt

The following requirements should be satisfied:

• transformers: 3.0.0

Datasets

The datasets used in our paper are available here.

Scenarios

Following the paper, we show how to apply StructuralKD in four scenarios.

Teacher and Student Share the Same Factorization Form

Linear-Chain CRF⇒Linear-ChainCRF

Teacher Models

We follow our previous work to train the CoNLL named entity recognition (NER) teachers. The teachers are available on google drive. Put these models in resources/taggers.

An alternative way is training the teacher models by yourself:

python train.py --config config/multi_bert_origflair_300epoch_2000batch_0.1lr_256hidden_de_monolingual_crf_sentloss_10patience_baseline_nodev_ner0.yaml #German
python train.py --config config/multi_bert_origflair_300epoch_2000batch_0.1lr_256hidden_en_monolingual_crf_sentloss_10patience_baseline_nodev_ner0.yaml #English
python train.py --config config/multi_bert_origflair_300epoch_2000batch_0.1lr_256hidden_es_monolingual_crf_sentloss_10patience_baseline_nodev_ner1.yaml #Spanish
python train.py --config config/multi_bert_origflair_300epoch_2000batch_0.1lr_256hidden_nl_monolingual_crf_sentloss_10patience_baseline_nodev_ner1.yaml #Dutch

Training Student Models

Run:

python train.py --config config/en_crf_ner.yaml #English
python train.py --config config/de_crf_ner.yaml #German
python train.py --config config/nl_crf_ner.yaml #Dutch
python train.py --config config/es_crf_ner.yaml #Spanish

Graph-based Dependency Parsing⇒Dependency Parsing as Sequence Labeling

Teacher Models

The code is aviable in the branch DepKD. We follow the biaffine parser to train the graph-based dependency parser. The teachers are available on google drive. Put these models in resources/taggers.

An alternative way is training the teacher models by yourself:

python train.py --config config/word_char_500epoch_0.5inter_5000batch_0.002lr_400hidden_ptb_monolingual_nocrf_fast_freeze_nodev_dependency30.yaml

Training Student Models

Run:

python train.py --config config/ptb-dp_as_sl-1st.yaml

---

Student Factorization Produces More Fine-grained Substructures than Teacher Factorization

Linear-Chain CRF⇒MaxEnt

Teacher Models

The teacher models are identical to the models in Linear-Chain CRF⇒Linear-ChainCRF.

Training Student Models

Run:

python train.py --config config/en_maxent_ner.yaml #English
python train.py --config config/de_maxent_ner.yaml #German
python train.py --config config/nl_maxent_ner.yaml #Dutch
python train.py --config config/es_maxent_ner.yaml #Spanish

Second-Order Dependency Parsing⇒Dependency Parsing as Sequence Labeling

Teacher Models

The code is aviable in the branch DepKD. We follow our previous model to train the graph-based second-order dependency parser. The teachers are available on google drive. Put these models in resources/taggers.

An alternative way is training the teacher models by yourself:

python train.py --config config/word_char_500epoch_0.5inter_5000batch_0.002lr_400hidden_ptb_monolingual_2nd_nocrf_fast_freeze_nodev_dependency30.yaml

Training Student Models

Run:

python train.py --config config/ptb-dp_as_sl-2nd.yaml

---

Teacher Factorization Produces More Fine-grained Substructures than Student Factorization

MaxEnt⇒Linear-Chain CRF

Teacher Model

The teacher is a multilingual teacher trained on WikiAnn datasets with four languages (Dutch, English, German, Spanish) The teacher is available on google drive. Put these models in resources/taggers.

Similarly, the teacher model can be trained by yourself:

python train.py --config config/multi-bert_10epoch_32batch_0.00005lr_10000lrrate_multilingual_nocrf_fast_relearn_sentbatch_sentloss_finetune_conlllang_nodev_panx_ner9.yaml

Training Student Models

In this case, we train the student model for four zero shot langauges, i.e. Basque, Hebrew, Persian and Tamil.

For each language, run:

python train.py --config config/ta_ner.yaml
python train.py --config config/fa_ner.yaml
python train.py --config config/eu_ner.yaml
python train.py --config config/he_ner.yaml

---

Factorization Forms From Teacher and Student are Incompatible

NER as Parsing => MaxEnt

Teacher Models

The code is available in the branch "case4". We follow previous work to train the named entity recognition(NER) teachers on CoNLL/WikiAnn datasets, the teachers are available here. Unzip the files to ./saves

To train a teacher model by yourself, you can follow the example command as follow:

python train.py --config configs/conll_teachers/conll03_bs3500_lr1e-3_epoch1k1_flair_fastword_bert_de.yaml  

All config files are available in configs/conll_teachers and configs/wikiann_teachers

Training Student Models

The example command to train a baseline student model:

python train.py --config configs/train_students/baselines/conll_baseline_de.yaml    # CoNLL datasets, German
python train.py --config configs/train_students/baselines/wikiann_baseline_en.yaml    # WikiAnn datasets, English

The example command to train a student model with structural knowledge distillation:

python train.py --config configs/train_students/kd/conll_kd_es.yaml # CoNLL datasets, Spanish
python train.py --config configs/train_students/kd/wikiann_kd_nl.yaml # WikiAnn datasets, Dutch
python train.py --config configs/train_students/kd/wikiann_3k_kd_de.yaml # WikiAnn datasets with 3k unlabeled sentences, German

All config files are availabel in configs/train_students

---

Train on Your Own Dataset

To set the dataset manully, you can set the dataset in the $config_file by:

targets: ner
ner:
  Corpus: ColumnCorpus-1
  ColumnCorpus-1: 
    data_folder: datasets/conll_03_english
    column_format:
      0: text
      1: pos
      2: chunk
      3: ner
    tag_to_bioes: ner
  tag_dictionary: resources/taggers/your_ner_tags.pkl

The tag_dictionary is a path to the tag dictionary for the task. If the path does not exist, the code will generate a tag dictionary at the path automatically. The dataset format is: Corpus: $CorpusClassName-$id, where $id is the name of datasets (anything you like). You can train multiple datasets jointly. For example:

Please refer to Config File for more details.

Parse files

If you want to parse a certain file, add train in the file name and put the file in a certain $dir (for example, parse_file_dir/train.your_file_name). Run:

CUDA_VISIBLE_DEVICES=0 python train.py --config $config_file --parse --target_dir $dir --keep_order

The format of the file should be column_format={0: 'text', 1:'ner'} for sequence labeling or you can modifiy line 232 in train.py. The parsed results will be in outputs/. Note that you may need to preprocess your file with the dummy tags for prediction, please check this issue for more details.

Config File

The config files are based on yaml format.

• targets: The target task
  • ner: named entity recognition
  • upos: part-of-speech tagging
  • chunk: chunking
  • ast: abstract extraction
  • dependency: dependency parsing
  • enhancedud: semantic dependency parsing/enhanced universal dependency parsing
• ner: An example for the targets. If targets: ner, then the code will read the values with the key of ner.
  • Corpus: The training corpora for the model, use : to split different corpora.
  • tag_dictionary: A path to the tag dictionary for the task. If the path does not exist, the code will generate a tag dictionary at the path automatically.
• target_dir: Save directory.
• model_name: The trained models will be save in $target_dir/$model_name.
• model: The model to train, depending on the task.
  • FastSequenceTagger: Sequence labeling model. The values are the parameters.
  • SemanticDependencyParser: Syntactic/semantic dependency parsing model. The values are the parameters.
• embeddings: The embeddings for the model, each key is the class name of the embedding and the values of the key are the parameters, see flair/embeddings.py for more details. For each embedding, use $classname-$id to represent the class. For example, if you want to use BERT and M-BERT for a single model, you can name: TransformerWordEmbeddings-0, TransformerWordEmbeddings-1.
• trainer: The trainer class.
  • ModelFinetuner: The trainer for fine-tuning embeddings or simply train a task model without ACE.
  • ReinforcementTrainer: The trainer for training ACE.
• train: the parameters for the train function in trainer (for example, ReinforcementTrainer.train()).

Citing Us

If you feel the code helpful, please cite:

@inproceedings{wang2021improving,
    title = "{{Improving Named Entity Recognition by External Context Retrieving and Cooperative Learning}}",
    author={Wang, Xinyu and Jiang, Yong and Bach, Nguyen and Wang, Tao and Huang, Zhongqiang and Huang, Fei and Tu, Kewei},
    booktitle = "{the Joint Conference of the 59th Annual Meeting of the Association for Computational Linguistics and the 11th International Joint Conference on Natural Language Processing (\textbf{ACL-IJCNLP 2021})}",
    month = aug,
    year = "2021",
    publisher = "Association for Computational Linguistics",
}

Contact

Feel free to email your questions or comments to issues or to Xinyu Wang.