Towards Being Parameter-Efficient: A Stratified Sparsely Activated Transformer with Dynamic Capacity

Haoran Xu, Maha Elbayad, Kenton Murray, Jean Maillard, Vedanuj Goswami


Abstract
Mixture-of-experts (MoE) models that employ sparse activation have demonstrated effectiveness in significantly increasing the number of parameters while maintaining low computational requirements per token. However, recent studies have established that MoE models are inherently parameter-inefficient as the improvement in performance diminishes with an increasing number of experts. We hypothesize this parameter inefficiency is a result of all experts having equal capacity, which may not adequately meet the varying complexity requirements of different tokens or tasks. In light of this, we propose Stratified Mixture of Experts (SMoE) models, which feature a stratified structure and can assign dynamic capacity to different tokens. We demonstrate the effectiveness of SMoE on three multilingual machine translation benchmarks, containing 4, 15, and 94 language pairs, respectively. We show that SMoE outperforms multiple state-of-the-art MoE models with the same or fewer parameters.
Anthology ID:
2023.findings-emnlp.856
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2023
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
12858–12870
Language:
URL:
https://aclanthology.org/2023.findings-emnlp.856
DOI:
10.18653/v1/2023.findings-emnlp.856
Bibkey:
Cite (ACL):
Haoran Xu, Maha Elbayad, Kenton Murray, Jean Maillard, and Vedanuj Goswami. 2023. Towards Being Parameter-Efficient: A Stratified Sparsely Activated Transformer with Dynamic Capacity. In Findings of the Association for Computational Linguistics: EMNLP 2023, pages 12858–12870, Singapore. Association for Computational Linguistics.
Cite (Informal):
Towards Being Parameter-Efficient: A Stratified Sparsely Activated Transformer with Dynamic Capacity (Xu et al., Findings 2023)
Copy Citation:
PDF:
https://aclanthology.org/2023.findings-emnlp.856.pdf