Learning to Abstract with Nonparametric Variational Information Bottleneck

Melika Behjati, Fabio Fehr, James Henderson


Abstract
Learned representations at the level of characters, sub-words, words, and sentences, have each contributed to advances in understanding different NLP tasks and linguistic phenomena. However, learning textual embeddings is costly as they are tokenization specific and require different models to be trained for each level of abstraction. We introduce a novel language representation model which can learn to compress to different levels of abstraction at different layers of the same model. We apply Nonparametric Variational Information Bottleneck (NVIB) to stacked Transformer self-attention layers in the encoder, which encourages an information-theoretic compression of the representations through the model. We find that the layers within the model correspond to increasing levels of abstraction and that their representations are more linguistically informed. Finally, we show that NVIB compression results in a model which is more robust to adversarial perturbations.
Anthology ID:
2023.findings-emnlp.106
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2023
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1576–1586
Language:
URL:
https://aclanthology.org/2023.findings-emnlp.106
DOI:
10.18653/v1/2023.findings-emnlp.106
Bibkey:
Cite (ACL):
Melika Behjati, Fabio Fehr, and James Henderson. 2023. Learning to Abstract with Nonparametric Variational Information Bottleneck. In Findings of the Association for Computational Linguistics: EMNLP 2023, pages 1576–1586, Singapore. Association for Computational Linguistics.
Cite (Informal):
Learning to Abstract with Nonparametric Variational Information Bottleneck (Behjati et al., Findings 2023)
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PDF:
https://aclanthology.org/2023.findings-emnlp.106.pdf
Video:
 https://aclanthology.org/2023.findings-emnlp.106.mp4