arXiv AI

MPQ: A Message-Passing View of Post-Training Quantization

The paper introduces Message-Passing Quantization (MPQ), a new approach to post‑training quantization (PTQ) that treats row‑wise PTQ as posterior inference over discrete codebooks. Unlike existing solvers that commit each weight block to a single codeword early, MPQ maintains soft posterior information across blocks using vector approximate message passing and only hard‑codes decisions at the final stage. Experiments on 2‑bit lattice and 3‑/4‑bit scalar quantization for dense language models from the Llama, Qwen, and Mistral families show that MPQ improves perplexity and zero‑shot accuracy compared to strong hard‑decision baselines and works well with preprocessing techniques such as activation‑aware scaling and incoherence processing.

arXiv Machine Learning
1d ago

Trainable Vector Quantization for Large Language Models

The paper introduces Trainable Vector Quantization (TVQ), a method that uses straight-through estimation to allow gradient descent optimization of vector-quantized large language models. TVQ reformulates VQ with trainable latent weights, enabling arbitrary objective minimization and is applied in a block-wise knowledge distillation framework to balance quality and training efficiency. Experiments show TVQ achieves state‑of‑the‑art low‑bit post‑training quantization, achieving near‑lossless 2‑bit quantization for LLaMA2‑70B with only a 1% accuracy drop on question‑answering benchmarks.

By Anastasiia Prutianova, Alina Bogdanova, Mikhail Shutov, Dmitrii Poimanov, Anatoly Gorkov, Ilia Zharikov
arXiv Machine Learning
Oct 22

Right On Q: Recovering Reasoning under Quantization via Self-Generated Trajectories

The paper introduces OnQ, a low‑bit recovery pipeline for quantized large language models that uses on‑policy distillation and candidate‑wise Dynamic KL to address trajectory divergence and distributional misalignment. OnQ starts with block‑wise calibration, then lets the quantized student generate responses and receive full‑precision teacher supervision on its own prefixes, dynamically weighting forward and reverse KL losses per candidate. Experiments on Qwen3 models show that OnQ outperforms baselines on nine benchmarks, especially long‑horizon reasoning, and produces shorter, less truncated responses.

By Boyuan Zheng, Jing Xiong, Chenwei Wu, Hui Shen, Zesen Zhao, Hei Ting Una Chan, Xueshen Liu, Zhen Zhang, Liyue Shen, Zechun Liu, Z. Morley Mao
arXiv Machine Learning
Oct 2

RATIO: Reasoning Analysis and Token-level Inference Optimization for Quantized Reasoning Models

The paper introduces RATIO, a framework for improving quantized reasoning models by identifying overthinking tokens and applying token-specific penalties. It uses Quantization-aware Reasoning Behavior Analysis to detect problematic tokens and Token-Specific Penalty Determination to assign penalties without extra training. Experiments show RATIO outperforms existing methods, boosting accuracy by up to 9.8 points and shortening chain-of-thought length by up to 51.3%.

By Chengzhu Bao, Xianglong Yan, Tianao Zhang, Jiaqi Chen, Shaoqiu Zhang, Yulun Zhang