OPRD: On-Policy Representation Distillation
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Abstract (arXiv)
On-policy distillation (OPD) supervises the student exclusively in the output space by matching next-token distributions. This paradigm suffers from two limitations: (i) a high-variance gradient estimator whose signal-to-noise ratio collapses as the student approaches the teacher, and (ii) an LM-head information bottleneck that discards the teacher's intermediate hidden states. We propose On-Policy Representation Distillation (OPRD), the first method to lift on-policy distillation into the hidden-state space. OPRD aligns student and teacher representations across selected layers on the same on-policy rollouts, providing dense, deterministic, per-layer supervision while bypassing the LM head entirely. Theoretically, OPRD provides a deterministic per-sample gradient, removing the token-level estimation variance that plagues OPD, and exposes structural information that any output-space objective necessarily discards. Empirically, OPRD closes the student-teacher gap on competition mathematics benchmarks (AIME 2024, AIME 2025, and AIMO), where every output-space baseline plateaus below the teacher, while training 1.44x faster and using up to 54% less memory. We further extend OPRD to the cross-architecture setting via OPRD-Bridge. By exploiting the observation that heterogeneous models share a low-rank representational structure, we construct a frozen projector pair that aligns representations across arbitrary depth and width mismatches, shifting the alignment from the output space (which depends on a shared vocabulary) to the representation space. We validate OPRD-Bridge on both cross-architecture (Qwen3-4B -> Qwen3-1.7B-Base) and cross-tokenizer (Phi-4-mini-reasoning -> Qwen3-1.7B-Base) settings, demonstrating successful knowledge transfer even when the vocabulary-based alignment channel is unavailable. Code: https://github.com/ShenzhiYang2000/OPRD.
Key facts. Cited by 9 papers in the map (data through 7 Oct 2026). Builds on 47 of its 49 references that are in the map. First posted on arXiv 4 Jun 2026.
Builds on
47 of 49 references.
References · 47
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35 more
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Built on by
Citing papers per year: 2026: 9.
9 papers.
- 2026Weak-to-Strong On-Policy Distillationcited by 7
- 2026Mismatch Matters: On-Policy Distillation Beyond Token Agreementcited by 7
- 2026Cliff: Learning Process Rewards from the First Mistakecited by 1
- 2026Negative Self-Distillation: Learning to Reason by Avoiding Flawscited by 1
- 2026SCOPE-OPSD: Fisher-Conditioned Privileged Subspaces for On-Policy Self-Distillationcited by 1
- 2026LastOPD: Taming Collapse in Latent On-Policy Distillationcited by 1
- 2026Teach Yourself Where to Look: On-Policy Attention Self-Distillation for Reasoningcited by 0
- 2026The Teacher Is a Direction, Not a Destination: Extrapolating RL-Induced Representation Residuals in On-Policy Distillationcited by 0
- 2026PR-OPD: Privileged Representation On-policy Self-Distillation for Agentic Reinforcement Learningcited by 0
- 2026PR-OPD: Privileged Representation On-policy Self-Distillation for Agentic Reinforcement Learning29 Sep 2026
- 2026The Teacher Is a Direction, Not a Destination: Extrapolating RL-Induced Representation Residuals in On-Policy Distillation29 Sep 2026
- 2026Teach Yourself Where to Look: On-Policy Attention Self-Distillation for Reasoning27 Sep 2026
- 2026LastOPD: Taming Collapse in Latent On-Policy Distillation23 Sep 2026
- 2026SCOPE-OPSD: Fisher-Conditioned Privileged Subspaces for On-Policy Self-Distillation11 Sep 2026
- 2026Negative Self-Distillation: Learning to Reason by Avoiding Flaws10 Sep 2026
- 2026Cliff: Learning Process Rewards from the First Mistake2 Sep 2026
- 2026Mismatch Matters: On-Policy Distillation Beyond Token Agreement10 Aug 2026
- 2026Weak-to-Strong On-Policy Distillation28 Jul 2026