ReFusion: Improving Natural Language Understanding with Computation-Efficient Retrieval Representation Fusion
Authors: Shangyu Wu,Ying Xiong,Yufei CUI,Xue Liu,Buzhou Tang,Tei-Wei Kuo,Chun Jason Xue
Presentation: ICLR 2024,Poster

Abstract: Retrieval-based augmentations (RA) incorporating knowledge from an external database into language models have greatly succeeded in various knowledge-intensive (KI) tasks. However, integrating retrievals in non-knowledge-intensive (NKI) tasks is still challenging.
Existing works focus on concatenating retrievals with inputs to improve model performance. Unfortunately, the use of retrieval concatenation-based augmentations causes an increase in the input length, substantially raising the computational demands of attention mechanisms.
This paper proposes a new paradigm of RA named \textbf{ReFusion}, a computation-efficient \textbf{Re}trieval representation \textbf{Fusion} with bi-level optimization. Unlike previous works, ReFusion directly fuses the retrieval representations into the hidden states of models.
Specifically, ReFusion leverages an adaptive retrieval integrator to seek the optimal combination of the proposed ranking schemes across different model layers. Experimental results demonstrate that the proposed ReFusion can achieve superior and robust performance in various NKI tasks.