Abstract
Traditional (unstructured) pruning methods for a Transformer model focus on regularizing the individual weights by penalizing them toward zero. In this work, we explore spectral-normalized identity priors (SNIP), a structured pruning approach which penalizes an entire residual module in a Transformer model toward an identity mapping. Our method identifies and discards unimportant non-linear mappings in the residual connections by applying a thresholding operator on the function norm, and is applicable to any structured module including a single attention head, an entire attention blocks, or a feed-forward subnetwork. Furthermore, we introduce spectral normalization to stabilize the distribution of the post-activation values of the Transformer layers, further improving the pruning effectiveness of the proposed methodology. We conduct experiments with BERT on 5 GLUE benchmark tasks to demonstrate that SNIP achieves effective pruning results while maintaining comparable performance. Specifically, we improve the performance over the state-of-the-art by 0.5 to 1.0% on average at 50% compression ratio.- Anthology ID:
- 2020.findings-emnlp.64
- Volume:
- Findings of the Association for Computational Linguistics: EMNLP 2020
- Month:
- November
- Year:
- 2020
- Address:
- Online
- Venue:
- Findings
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 719–730
- Language:
- URL:
- https://aclanthology.org/2020.findings-emnlp.64
- DOI:
- 10.18653/v1/2020.findings-emnlp.64
- Cite (ACL):
- Zi Lin, Jeremiah Liu, Zi Yang, Nan Hua, and Dan Roth. 2020. Pruning Redundant Mappings in Transformer Models via Spectral-Normalized Identity Prior. In Findings of the Association for Computational Linguistics: EMNLP 2020, pages 719–730, Online. Association for Computational Linguistics.
- Cite (Informal):
- Pruning Redundant Mappings in Transformer Models via Spectral-Normalized Identity Prior (Lin et al., Findings 2020)
- PDF:
- https://preview.aclanthology.org/ingestion-script-update/2020.findings-emnlp.64.pdf
- Code
- google-research/google-research
- Data
- GLUE, MRPC, MultiNLI, QNLI, SST