Train Overcomplete, Deploy Compact: Scaling Recovery Capacity for Structured LLM Pruning

Seungmin Oh, Donggeon Lee, Jongbin Ryu


Abstract
Large language models achieve strong performance across diverse tasks, but deployment remains costly because of memory, latency, and energy demands. Structured pruning reduces these costs by removing architectural components, yet its recovery stage is often limited by a mismatch between the recovery module’s representational capacity and the complexity of the removed knowledge. We call this bottleneck the capacity-knowledge asymmetry and propose **OverRep**, an **Over**complete **Rep**arameterization framework for structured LLM pruning. Following the principle of *“train overcomplete, deploy compact”*, OverRep temporarily overparameterizes the recovery module during training to absorb complex knowledge distilled from the original model. After recovery, the overcomplete re-parameterization is algebraically merged into a mathematically equivalent compact module, preserving the pruned model’s inference-time architecture and computational cost. OverRep further introduces an annealed activation that enables nonlinear training dynamics while converging to a linear regime for exact algebraic merging. Across three backbone families, OverRep improves retained reasoning performance over strong recovery baselines by up to 5.5 and 8.4 points at 25% and 50% pruning, respectively, while keeping memory usage and TFLOPs comparable to existing recovery methods. Our code is available at https://github.com/mmai-laboratory/OverRep
Anthology ID:
2026.emnlp-main.278
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
6336–6355
Language:
URL:
https://aclanthology.org/2026.emnlp-main.278/
DOI:
Bibkey:
Cite (ACL):
Seungmin Oh, Donggeon Lee, and Jongbin Ryu. 2026. Train Overcomplete, Deploy Compact: Scaling Recovery Capacity for Structured LLM Pruning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 6336–6355, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Train Overcomplete, Deploy Compact: Scaling Recovery Capacity for Structured LLM Pruning (Oh et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.278.pdf