arXiv Computation and Language
Oct 28

Watermark Basins: Black-Box Detection of Distilled LLMs

The paper introduces Watermark Basin Alignment (WM‑Basin), a black‑box method for detecting distilled large language models (LLMs). It exploits a persistent watermark basin—a key‑specific geometric signal embedded in the teacher’s parameter space during fine‑tuning—that remains detectable even when token‑level signals vanish. WM‑Basin maps suspect model outputs to gradient representations, removes ordinary fine‑tuning directions, and tests alignment with the watermark basin, achieving significantly higher detection rates than token‑level baselines across a range of teacher and student models.

By Hongyan Chang, Hady Elsahar, Tom Sander, Pierre Fernandez, Saeed Mahloujifar, Sylvestre-Alvise Rebuffi, Tom\'a\v{s} Sou\v{c}ek, Tuan Tran, Valeriu Lacatusu, Surya Parimi, Rashel Moritz, Vanessa Stark, Alexandre Mourachko
arXiv AI
Jul 7

Reward-Gated On-Policy Distillation

arXiv:2607. 04037v1 Announce Type: cross Abstract: On-policy distillation is a powerful way to transfer reasoning ability from a strong teacher to a smaller student: the student samples trajectories from its own policy, and the teacher provides dense token-level supervision on the states the student actually visits.

By Mohammad Sadegh Akhondzadeh, Vijay Lingam, Atula Tejaswi, Chanakya Ekbote, Sujay Sanghavi, Aleksandar Bojchevski
arXiv AI
Oct 5

Harness-Aware Distillation for Small Language Model Agents

The paper introduces Harness-Aware Distillation (HAD), a method for training smaller language model agents that preserves the surrounding harness—software managing context, tools, and feedback—while focusing distillation on the teacher’s contributions beyond the harness. HAD combines an action preference that contrasts teacher actions with and without harness information, and a validity check that filters out contradictory preference pairs. Experiments on long-horizon agent benchmarks show that HAD outperforms standard on‑policy distillation, reducing unproductive loops and improving error recovery without requiring task rewards or future information.

By Moonseok Choi, Taehong Moon, Giung Nam, Juho Lee
arXiv AI
Jul 3

DemoPSD: Disagreement-Modulated Policy Self-Distillation

arXiv:2607. 02502v1 Announce Type: cross Abstract: On-policy self-distillation (OPSD) has emerged as a practical method for training large language models (LLMs) to reason, where a single model acts as both the teacher and the student with different levels of information access.

By Yunhe Li, Hao Shi, Wenhao Liu, Mengzhe Ruan, Hanxu Hou, Zhongxiang Dai, Shuang Qiu, Linqi Song