Towards Better Multi-head Attention via Channel-wise Sample Permutation

25 Sept 2024 (modified: 22 Nov 2024)ICLR 2025 Conference Withdrawn SubmissionEveryoneRevisionsBibTeXCC BY 4.0
Keywords: Efficient Transformers, sparse doubly stochastic attention, permutation, optimal transport
TL;DR: We propose a simple and novel channel-wise sample permutation (CSP) operator, achieving a new theoretically solid multi-head attention mechanism with lower complexity and competitive performance.
Abstract: Transformer plays a central role in many fundamental deep learning models, e.g., the ViT in computer vision and the BERT and GPT in natural language processing, whose effectiveness is mainly attributed to its multi-head attention (MHA) mechanism. In this study, we propose a simple and novel channel-wise sample permutation (CSP) operator, achieving a new structured MHA with fewer parameters and lower complexity. Given an input matrix, CSP circularly shifts the samples of different channels with various steps and then sorts grouped samples of each channel. This operator is equivalent to implicitly implementing cross-channel attention maps as permutation matrices, which achieves linear complexity and suppresses the risk of rank collapse when representing data. We replace the MHA of some representative models with CSP and test the CSP-based models in several discriminative tasks, including image classification and long sequence analysis. Experiments show that the CSP-based models achieve comparable or better performance with fewer parameters and lower computational costs than the classic Transformer and its state-of-the-art variants. The code is available at https://anonymous.4open.science/r/CSP-BA52.
Primary Area: foundation or frontier models, including LLMs
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