FiD-ICL: A Fusion-in-Decoder Approach for Efficient In-Context Learning

Qinyuan Ye, Iz Beltagy, Matthew Peters, Xiang Ren, Hannaneh Hajishirzi


Abstract
Large pre-trained models are capable of few-shot in-context learning (ICL), i.e., performing a new task by prepending a few demonstrations before the test input. However, the concatenated demonstrations are often excessively long and induce additional computation. Inspired by fusion-in-decoder (FiD) models which efficiently aggregate more passages and thus outperforms concatenation-based models in open-domain QA, we hypothesize that similar techniques can be applied to improve the efficiency and end-task performance of ICL. To verify this, we present a comprehensive study on applying three fusion methods—concatenation-based (early fusion), FiD (intermediate), and ensemble-based (late)—to ICL. We adopt a meta-learning setup where a model is first trained to perform ICL on a mixture of tasks using one selected fusion method, then evaluated on held-out tasks for ICL. Results on 11 held-out tasks show that FiD-ICL matches or outperforms the other two fusion methods. Additionally, we show that FiD-ICL (1) is 10x faster at inference time compared to concat-based and ensemble-based ICL, as we can easily pre-compute the representations of in-context examples and reuse them; (2) enables scaling up to meta-training 3B-sized models, which would fail for concat-based ICL.
Anthology ID:
2023.acl-long.454
Volume:
Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2023
Address:
Toronto, Canada
Editors:
Anna Rogers, Jordan Boyd-Graber, Naoaki Okazaki
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
8158–8185
Language:
URL:
https://aclanthology.org/2023.acl-long.454
DOI:
10.18653/v1/2023.acl-long.454
Bibkey:
Cite (ACL):
Qinyuan Ye, Iz Beltagy, Matthew Peters, Xiang Ren, and Hannaneh Hajishirzi. 2023. FiD-ICL: A Fusion-in-Decoder Approach for Efficient In-Context Learning. In Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 8158–8185, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
FiD-ICL: A Fusion-in-Decoder Approach for Efficient In-Context Learning (Ye et al., ACL 2023)
Copy Citation:
PDF:
https://aclanthology.org/2023.acl-long.454.pdf
Video:
 https://aclanthology.org/2023.acl-long.454.mp4