Rethinking Cross-Tokenizer On-Policy Distillation: From Alignment Coverage to Supervision Reliability
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The paper introduces Common‑Support Distillation (CSD), a logits‑based framework for transferring knowledge across different tokenizers by constructing a shared support between teacher and student distributions. CSD handles both one‑to‑one alignments using explicit common‑token pairs and other alignments by creating a virtual support via the autoregressive chain rule, while a residual event ensures normalization. Experiments on Llama‑3.2‑1B, Gemma3‑1B‑PT, Qwen, and Phi models show that CSD consistently outperforms existing cross‑tokenizer methods, achieving up to 1.8‑point gains over the best alternative and surpassing both continued pretraining and same‑tokenizer distillation.
arXiv:2606. 08432v1 Announce Type: new Abstract: On-policy distillation (OPD) has become a central post-training tool for large language models (LLMs), providing dense per-token teacher supervision along the student's own rollouts.
arXiv:2608. 03632v1 Announce Type: new Abstract: On-Policy distillation (OPD) transfers teacher capabilities by supervising student-sampled trajectories with dense token-level teacher signals.
arXiv:2605. 03677v2 Announce Type: replace Abstract: On-policy distillation (OPD) has recently emerged as an effective post-training paradigm for consolidating the capabilities of specialized expert models into a single student model.
arXiv:2601. 07155v3 Announce Type: replace-cross Abstract: Knowledge distillation (KD) is a widely adopted technique for transferring knowledge from large language models to smaller student models; however, conventional supervised KD often suffers from a distribution mismatch between training and inference.
On-Policy distillation (OPD) transfers teacher capabilities by supervising student-sampled trajectories with dense token-level teacher signals. Recent selective OPD methods improve this process by prioritizing signals that are confident, informative, or learnable.