Fixing MoE Over-Fitting on Low-Resource Languages in Multilingual Machine Translation

Maha Elbayad, Anna Sun, Shruti Bhosale


Abstract
Sparsely gated Mixture of Experts (MoE) models have been shown to be a compute-efficient method to scale model capacity for multilingual machine translation. However, for low-resource tasks, MoE models severely over-fit. We show effective regularization strategies, namely dropout techniques for MoE layers in EOM and FOM, Conditional MoE Routing and Curriculum Learning methods that prevent over-fitting and improve the performance of MoE models on low-resource tasks without adversely affecting high-resource tasks. On a massively multilingual machine translation benchmark, our strategies result in about +1 chrF++ improvement in very low resource language pairs. We perform an extensive analysis of the learned MoE routing to better understand the impact of our regularization methods and how we can improve them.
Anthology ID:
2023.findings-acl.897
Volume:
Findings of the Association for Computational Linguistics: ACL 2023
Month:
July
Year:
2023
Address:
Toronto, Canada
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
14237–14253
Language:
URL:
https://aclanthology.org/2023.findings-acl.897
DOI:
10.18653/v1/2023.findings-acl.897
Bibkey:
Cite (ACL):
Maha Elbayad, Anna Sun, and Shruti Bhosale. 2023. Fixing MoE Over-Fitting on Low-Resource Languages in Multilingual Machine Translation. In Findings of the Association for Computational Linguistics: ACL 2023, pages 14237–14253, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
Fixing MoE Over-Fitting on Low-Resource Languages in Multilingual Machine Translation (Elbayad et al., Findings 2023)
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PDF:
https://preview.aclanthology.org/remove-xml-comments/2023.findings-acl.897.pdf