The state-of-the-art Mixture-of-Experts (short as MoE) architecture has achieved several remarkable successes in terms of increasing model capacity. However, MoE has been hindered widespread adoption due to complexity, communication costs, and training instability. Here we present a novel MoE architecture based on matrix product operators (MPO) from quantum many-body physics. It can decompose an original matrix into central tensors (containing the core information) and auxiliary tensors (with only a small proportion of parameters). With the decomposed MPO structure, we can reduce the parameters of the original MoE architecture by sharing a global central tensor across experts and keeping expert-specific auxiliary tensors. We also design the gradient mask strategy for the tensor structure of MPO to alleviate the overfitting problem. Experiments on the three well-known downstream natural language datasets based on GPT2 show improved performance and efficiency in increasing model capacity (7.26x fewer parameters with the same amount of experts). We additionally demonstrate an improvement in the positive transfer effects of our approach for multi-task learning.

本文提出了一种参数高效的混合专家架构，通过在专家层中共享参数矩阵中心张量的信息，并通过辅助张量增加各个专家的特异性，从而通过矩阵乘积算子来实现受量子多体物理学影响的张量分解，以解决混合专家架构中存在的参数膨胀问题，实验结果表明新方法具有更好的性能和效率。

预训练语言模型的参数高效专家混合架构