Historical trajectories provide step-level credit for training LLM agents via regressor

T2SPO uses a frozen TabPFN to estimate remaining distance to success at each state, deriving auxiliary step rewards from past successful rollouts to improve policy learning.

Chinese Tech
Bo-Wen Zhang · Junwei He · Maoqi Liu · Feiran Li · Song-Lin Lv · Wentao Ma · +3 more

Nanjing University · ByteDance

Research Digest··3 min read
Zhang et al.

Why this paper

From ByteDance and Nanjing University · Part of Credit Assignment in Agentic RL, now 28 papers

In one line

T2SPO derives step-level credit from past successful trajectories using a frozen TabPFN regressor, improving LLM agent task success over GRPO.

What we could check

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