ResearchResearch paperReinforcement Learning · Efficiency & Inference · Interpretability1 source · Oct 16, 2026

Bootstrap Stochastic Interpolant Tree for Inference-time Search Under Sparse Reward

Tree-based samplers offer a compelling alternative for scalable inference-time search, bypassing the per-step reward and gradient dependencies that introduce systematic bias into SMC-style frameworks.

Key points

  • Their reliance on learned, DDPM-like transitions inherently couples neighbor states in a trajectory, thereby restricting child-parent feature divergence in the tree sampler.
  • To overcome these limitations, we introduce a simple yet effective Bootstrap Stochastic Interpolant Tree (BSIT) sampler that decouples child node generation from explicit parent dependencies.
  • By expanding the degrees of freedom during child node sampling, BSIT encourages diverse trajectory rollouts and unlocks broader path-space diversity-the exact catalyst needed for efficient exploration.
  • Crucially, we show that BSIT's improved exploration accelerates convergence to the target distribution while achieving broader distributional coverage than samplers that rely on DDPM-like transitions for child-node generation, all without incurring additional function evaluations or reward feedback, thereby providing a highly efficient basis for rare target search.

Sources (1)

  • [1]Bootstrap Stochastic Interpolant Tree for Inference-time Search Under Sparse Reward
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 16, 08:03 PM
    Tree-based samplers offer a compelling alternative for scalable inference-time search, bypassing the per-step reward and gradient dependencies that introduce systematic bias into SMC-style frameworks.
    Their reliance on learned, DDPM-like transitions inherently couples neighbor states in a trajectory, thereby restricting child-parent feature divergence in the tree sampler.

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