Revisiting Judge Decoding from First Principles via Training-Free Distributional Divergence

Fuente: arXiv
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Autori principali: Sun, Shengyin, Li, Yiming, Liu, Renxi, Lin, Weizhe, Zhen, Hui-Ling, Yu, Xianzhi, Yuan, Mingxuan, Ma, Chen
Natura: Preprint
Pubblicazione: 2026
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author Sun, Shengyin
Li, Yiming
Liu, Renxi
Lin, Weizhe
Zhen, Hui-Ling
Yu, Xianzhi
Yuan, Mingxuan
Ma, Chen
author_facet Sun, Shengyin
Li, Yiming
Liu, Renxi
Lin, Weizhe
Zhen, Hui-Ling
Yu, Xianzhi
Yuan, Mingxuan
Ma, Chen
contents Judge Decoding accelerates LLM inference by relaxing the strict verification of Speculative Decoding, yet it typically relies on expensive and noisy supervision. In this work, we revisit this paradigm from first principles, revealing that the ``criticality'' scores learned via costly supervision are intrinsically encoded in the draft-target distributional divergence. We theoretically prove a structural correspondence between learned linear judges and Kullback-Leibler (KL) divergence, demonstrating they rely on the same underlying logit primitives. Guided by this, we propose a simple, training-free verification mechanism based on KL divergence. Extensive experiments across reasoning and coding benchmarks show that our method matches or outperforms complex trained judges (e.g., AutoJudge), offering superior robustness to domain shifts and eliminating the supervision bottleneck entirely.
format Preprint
id arxiv_https___arxiv_org_abs_2601_04766
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Revisiting Judge Decoding from First Principles via Training-Free Distributional Divergence
Sun, Shengyin
Li, Yiming
Liu, Renxi
Lin, Weizhe
Zhen, Hui-Ling
Yu, Xianzhi
Yuan, Mingxuan
Ma, Chen
Computation and Language
Judge Decoding accelerates LLM inference by relaxing the strict verification of Speculative Decoding, yet it typically relies on expensive and noisy supervision. In this work, we revisit this paradigm from first principles, revealing that the ``criticality'' scores learned via costly supervision are intrinsically encoded in the draft-target distributional divergence. We theoretically prove a structural correspondence between learned linear judges and Kullback-Leibler (KL) divergence, demonstrating they rely on the same underlying logit primitives. Guided by this, we propose a simple, training-free verification mechanism based on KL divergence. Extensive experiments across reasoning and coding benchmarks show that our method matches or outperforms complex trained judges (e.g., AutoJudge), offering superior robustness to domain shifts and eliminating the supervision bottleneck entirely.
title Revisiting Judge Decoding from First Principles via Training-Free Distributional Divergence
topic Computation and Language
url https://arxiv.org/abs/2601.04766