On the Effectiveness of Discrete Representations in Sparse Mixture of Experts

Giang Do, Kha Pham, Hung Le, Truyen Tran

Keywords: Sparse mixture of experts, discrete representations, vector quantization, large language model

TL;DR: We introduce a novel and effective architecture that selects experts by learning discrete representations

Abstract:

Sparse mixture of experts (SMoE) is an effective solution for scaling up model capacity without increasing the computational costs. A crucial component of SMoE is the router, responsible for directing the input to relevant experts; however, it also presents a major weakness, leading to routing inconsistencies and representation collapse issues. Instead of fixing the router like previous works, we propose an alternative that assigns experts to input via indirection, which employs the discrete representation of input that points to the expert. The discrete representations are learnt via vector quantization, resulting in a new architecture dubbed VectorQuantized Mixture of Experts (VQMoE). We provide theoretical support and empirical evidence demonstrating the VQMoE’s ability to overcome the challenges present in traditional routers. Through extensive evaluations on both large language models and vision tasks for pre-training and fine-tuning, we show that VQMoE achieves a 28% improvement in robustness compared to other SMoE routing methods, while maintaining strong performance in fine-tuning tasks.

Primary Area: foundation or frontier models, including LLMs

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Submission Number: 8518