A Simple Language Model for Task-Oriented Dialogue
Paper · 2020 · Ehsan Hosseini-Asl, Bryan McCann, Chien-Sheng Wu et al.
Summary
Dialogue systems that help a user accomplish a specific task (task-oriented dialogue, TOD) are usually built as a pipeline of separate modules. One module tracks the dialogue state (belief state), a second selects system actions, and a third generates the response. Because of this division, errors from one module propagate to the subsequent ones. Researchers from Salesforce Research propose SimpleTOD, a single causal language model that solves all three subtasks as a single sequence prediction task. The model reads the dialogue history and generates the belief state. It then receives aggregated results of the database query and generates the actions and a delexicalized response. The weights are taken from GPT-2 or DistilGPT2, and the model is fine-tuned on MultiWOZ 2.1. Greedy decoding is sufficient for generation. SimpleTOD outperformed previous methods both in dialogue state tracking and in end-to-end evaluation of actions and responses. Thus, the knowledge the model acquired during pre-training on general text transfers well to target dialogues, and a cumbersome modular architecture can be replaced with a simple one. The authors released the code, a list of erroneous annotations in MultiWOZ, and a cleaned version of the test set.
Key points
- Joint goal accuracy on MultiWOZ 2.1 is 55.76, the best result for state tracking at the time of publication. In the end-to-end setting, the inform rate increased by 8.1 points, the success rate by 9.7, and the combined score by 7.2.
- Special tokens are critically important. Without end-of-segment markers and without user/system turn tagging, joint accuracy drops to 16.79, and the combined score falls from 92.98 to 26.73.
- Without pre-training, the model performs much worse: a 12-layer model with random weights achieves a joint accuracy of 20.17 versus 55.76 for GPT-2. A larger model is not always better: DistilGPT2 yields a combined score of 92.98, while GPT-2 yields 90.75.
- The authors identified four types of erroneous annotations in MultiWOZ 2.1 and showed that SimpleTOD is robust to such noise.
- The code, the cleaned test set, and the list of annotation errors were released on GitHub: salesforce/simpletod. The paper was published at NeurIPS 2020.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 works
🧭 Topics 2Research subjects and languages the work is about.Language models & pretraining · 3,320 worksDialogue systems · 624 works
💡 Concepts 1Key ideas and methods explained on our concept pages.Chatbots · 54 works
Cite
Cite as Ehsan Hosseini-Asl, Bryan McCann, Chien-Sheng Wu, Semih Yavuz and Richard Socher. 2020. A Simple Language Model for Task-Oriented Dialogue. arXiv:2005.00796.
@misc{hosseiniasl2020simple,
title = {{A Simple Language Model for Task-Oriented Dialogue}},
author = {Ehsan Hosseini-Asl, Bryan McCann, Chien-Sheng Wu, Semih Yavuz and Richard Socher},
year = {2020},
doi = {10.48550/arxiv.2005.00796},
eprint = {2005.00796},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2005.00796}
}References
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