ROCOB: Dual-Manifold Alignment with Optimal Budgeting for Training-Free PTQ Recovery

Haoqi Yang, Teng Xiao, Zuchao Li, Hao Huang, Lefei Zhang, Hai Zhao


Abstract
Post-training quantization facilitates efficient LLM deployment, yet it disproportionately erodes reasoning and mathematical performance. To recover fidelity without costly fine-tuning, we identify a critical vulnerability in existing output-space methods: the tendency to overfit the limited calibration manifold, which necessitates structural regularization for unseen data. We propose **ROCOB** (**R**esilient **O**utput **C**ompensation with **O**ptimal **B**udgeting), a training-free framework based on *Dual-Manifold Alignment*. ROCOB couples a Principal Activation Component (PAC), which minimizes error on the calibration manifold, with an Orthogonal Geometric Component (OGC), which recovers residual weight-space structure without fitting a second calibration objective. To compare methods fairly under the same added-parameter budget, ROCOB uses Global Spectral Energy Maximization (GSEM) to allocate ranks according to recovered spectral energy and module cost. Across Qwen3 and Llama-3 models, quantizers, and reasoning benchmarks, ROCOB improves average post-quantization recovery in most evaluated model–quantizer settings while preserving a training-free construction pipeline.
Anthology ID:
2026.aacl-long.158
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3491–3512
Language:
URL:
https://aclanthology.org/2026.aacl-long.158/
DOI:
Bibkey:
Cite (ACL):
Haoqi Yang, Teng Xiao, Zuchao Li, Hao Huang, Lefei Zhang, and Hai Zhao. 2026. ROCOB: Dual-Manifold Alignment with Optimal Budgeting for Training-Free PTQ Recovery. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 3491–3512, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
ROCOB: Dual-Manifold Alignment with Optimal Budgeting for Training-Free PTQ Recovery (Yang et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.158.pdf