TL;DR
Reinforcement learning with verifiable rewards (RLVR) struggles with low-variance feedback due to simplistic or complex prompts. TRACE, or Tree Rollout Allocation for Contrastive Exploration, is a new framework that allocates rollout budgets to both prompt roots and intermediate prefixes to enhance reward contrast.
✦ Why It Matters
Engineers can leverage TRACE to enhance the efficiency and effectiveness of reinforcement learning models in practical applications.
Key Takeaways
Full Summary
Reinforcement learning with verifiable rewards (RLVR) aims to improve reasoning and decision-making in large language models but often faces challenges due to insufficient reward contrast. Traditional methods focus on optimizing rollout resources at the prompt level, overlooking the variation in informativeness across different turns in multi-turn interactions.
TRACE, or Tree Rollout Allocation for Contrastive Exploration, addresses this by modeling each turn as a distinct node in a tree structure, allowing for more nuanced budget allocation. It allocates resources to both the initial prompts and their subsequent prefixes, targeting those most likely to yield diverse terminal rewards.
A shared predictor estimates the success probability at these points, guiding the allocation process. Empirical results show that TRACE enhances performance on standard benchmarks, achieving a 2.8-point increase in accuracy for Qwen3-14B Multi-Hop QA.
This framework not only improves efficiency but also enriches the feedback received during training.
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