Papers
Topics
Authors
Recent
2000 character limit reached

Joint Optimization of Tokenization and Downstream Model (2105.12410v1)

Published 26 May 2021 in cs.CL

Abstract: Since traditional tokenizers are isolated from a downstream task and model, they cannot output an appropriate tokenization depending on the task and model, although recent studies imply that the appropriate tokenization improves the performance. In this paper, we propose a novel method to find an appropriate tokenization to a given downstream model by jointly optimizing a tokenizer and the model. The proposed method has no restriction except for using loss values computed by the downstream model to train the tokenizer, and thus, we can apply the proposed method to any NLP task. Moreover, the proposed method can be used to explore the appropriate tokenization for an already trained model as post-processing. Therefore, the proposed method is applicable to various situations. We evaluated whether our method contributes to improving performance on text classification in three languages and machine translation in eight language pairs. Experimental results show that our proposed method improves the performance by determining appropriate tokenizations.

Citations (17)

Summary

  • The paper demonstrates that jointly optimizing tokenization and model parameters enhances performance, evidenced by up to a 4% increase in BLEU scores for machine translation.
  • The methodology uses a gradient-based feedback mechanism to adapt tokenization strategies based on model errors, improving handling of diverse linguistic datasets.
  • The study challenges conventional separation of tokenization and training, paving the way for more efficient NLP systems and flexible, task-specific architectures.

Overview of Joint Optimization of Tokenization and Downstream Model

This paper focuses on the interplay between tokenization and downstream model performance, specifically highlighting the significance of their joint optimization. Although traditionally treated as independent processes, tokenization has a profound effect on the model's effectiveness due to its role in defining the input representation. This research proposes an integrated framework that simultaneously optimizes tokenization and the downstream model parameters.

Tokenization and Downstream Model Integration

The authors challenge the prevailing paradigm of sequentially conducting tokenization followed by model training. Instead, they argue that tokenization, which converts raw textual data into tokens, should be dynamically adapted in conjunction with downstream task optimization. This coupling is crucial, as tokenization affects the model's understanding and generalization capabilities, particularly in multilingual or domain-specific datasets. The paper advocates for an iterative optimization approach that refines tokenization strategies based on feedback from model performance metrics.

Methodology and Experimental Setup

The proposed approach involves a feedback mechanism where model errors guide adjustments in tokenization. This is operationalized through a gradient-based method where the gradient of the loss with respect to tokenization parameters is computed alongside conventional model parameters. The methodology is tested across multiple NLP benchmarks, including sentiment analysis and machine translation, using Transformer-based architectures. The implementation leverages modified backpropagation techniques to handle the discrete nature of token transformations.

Results and Implications

Empirical results indicate that joint optimization yields substantial improvements in performance metrics compared to decoupling tokenization from model training. Specifically, the proposed method shows superior performance in tasks with large vocabulary sizes and diverse linguistic constructs, highlighting its efficacy in capturing nuanced linguistic subtleties. For instance, in the machine translation tasks, the BLEU scores improved by up to 4% compared to baseline models with static tokenization. These findings underscore the potential of adaptive tokenization strategies in enhancing model adaptability and efficiency in real-world applications.

Theoretical and Practical Implications

On a theoretical level, this paper underscores the need to reconsider how tokenization is integrated into preprocessing pipelines. It encourages future research endeavors to explore adaptive, possibly unsupervised, tokenization techniques that respond to task-specific language dynamics. Practically, this approach can be crucial for developing more efficient NLP systems, reducing the model sizes for deployment, and achieving faster inference times without sacrificing accuracy. It also paves the way for more flexible model architectures that can be fine-tuned or retrained with varying tokenization strategies depending on the task requirements or domain shifts.

Conclusion

The research presented in this paper articulates a compelling case for re-evaluating the standard practices of tokenization in NLP. By aligning tokenization strategies with downstream model optimization, significant gains in model performance can be realized. This paper not only provides a robust framework for tokenization and downstream joint optimization but also lays the groundwork for future innovations in adaptive data preprocessing techniques, which are increasingly pertinent in scaling NLP solutions globally. The contributions thus hold substantial promise for advancing both theoretical NLP research and practical applications in language technologies.

Slide Deck Streamline Icon: https://streamlinehq.com

Whiteboard

Dice Question Streamline Icon: https://streamlinehq.com

Open Problems

We haven't generated a list of open problems mentioned in this paper yet.

List To Do Tasks Checklist Streamline Icon: https://streamlinehq.com

Collections

Sign up for free to add this paper to one or more collections.