LM-Corrector

Small Language Models Improve Giants by Rewriting Their Outputs
Giorgos Vernikos, Arthur Bražinskas, Jakub Adamek, Jonathan Mallinson, Aliaksei Severyn, Eric Malmi
European Chapter of the Association for Computational Linguistics (EACL) 2024

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Overview

LMCor is a novel method for enhancing the performance of Language Model Models (LLMs) by leveraging only their outputs. We introduce the LM-Corrector (LMCor), a small model designed to rank, combine, and edit diverse candidate outputs generated by LLMs, consistently outperforming in-context learning and reranking strategies.

This repository contains code for training a T5 (or similar) model as an LM-Corrector or for standard fine-tuning for text generation tasks. These tasks include grammatical error correction, data-to-text generation, summarization, and machine translation.

Installation

This project requires Python 3.10, PyTorch 1.12.1, and transformers 4.34.0.

It's advisable to set up a separate environment for this project and install the necessary dependencies:

conda create -n lmcor python=3.10
conda activate lmcor
pip install -r requirements.txt

Datasets

LMCor is evaluated on various tasks and datasets:

• Grammatical Error Correction: CoNLL-14
• Data-to-Text Generation: E2E NLG (cleaned)
• Summarization: XSum
• Machine Translation: WMT22 En->De

The code integrates E2E and XSum datasets via the Datasets library. For WMT22 En->De, you need to manually download the validation and test sets from sacreBLEU and store them in the data/wmt22/en-de/ folder with filenames validation.<x> and test.<x>, where <x> = en, de. For training, 200k sentences are sampled from News Commentary v16, available here.

Training LMCor

LLM-generated candidates

To train an LM-Corrector, you first need predictions for the training and validation sets from a Language Model (LLM). Assume these files are stored in the corresponding data/<task>/ folder as train_[llm_name] and validation_[llm_name]. In this project, we used the greedy decoded output along with 4 sampled outputs from the LLM. You can edit the filenames in the train_t5.py script using the FILE_SAMPLE and FILE_GREEDY global variables.

To train the corrector execute the train_t5.py script:

python train_t5.py --task xsum --corrector --bsize 8 --grad_acc_steps 16 --output_dir lmcor_xsum

Note: to train a standard t5 model remove the --corrector flag

To change the directory where the HuggingFace models are stored edit the MODELS_DIR global variable in the t5_utils.py script

Evaluate LMCor

To obtain predictions from the corrector, use the eval_t5.py script:

python eval_t5.py --task xsum --corrector --ckpt lmcor_xsum --split test --bsize 32 

The outputs of LMCor will be saved in the model folder in the file model_preds.txt.

Finally, to compute scores for various metrics, run the compute_textgen_metrics.py script:

python compute_textgen_metrics --task xsum --hyp lmcor_xsum/model_preds.txt

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Reference

Please feel free to cite our paper if you use our code or proposed algorithm.:

@inproceedings{vernikos-etal-2024-small,
    title = "Small Language Models Improve Giants by Rewriting Their Outputs",
    author = "Vernikos, Giorgos  and Brazinskas, Arthur  and Adamek, Jakub  and Mallinson, Jonathan  and Severyn, Aliaksei  and Malmi, Eric",
    booktitle = "Proceedings of the 18th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)",
    month = mar,
    year = "2024",
    address = "St. Julian{'}s, Malta",
    publisher = "Association for Computational Linguistics",
    url = "https://aclanthology.org/2024.eacl-long.165",
}

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Contact

Please feel free to raise an issue or contact me in case you require any help setting up the repo!