OPDSearch+: distill a frozen teacher then refine with RL to beat RL-only training

_reachsumit · x · 2026-08-26

arXiv paper OPDSearch+ proposes the first distillation paradigm for search-augmented reasoning that requires no teacher fine-tuning. Motivation: collecting multi-turn search trajectories for SFT is prohibitively expensive, while on-policy distillation with an off-the-shelf teacher is unstable and caps the student at the teacher's ceiling. Two stages: the student interacts with a live search engine and is distilled via per-position forward KL from a frozen instruct model, transferring reasoning decomposition and evidence-integration skills; then RL refines the distilled student. Key insight: the teacher reshapes the student's policy distribution so subsequent RL converges to solutions RL alone cannot reach, especially on multi-hop questions.

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