Necessity of chain-of-thought rationales for semantic equivalence verification

Determine whether chain-of-thought rationales are necessary for accurately assessing semantic equivalence between expert-written reference answers and model-generated responses in the same language when verification focuses on the concluding portion of the response.

Background

The paper simplifies verification by instructing a generative reward model to produce binary judgments (0 or 1) without requiring chain-of-thought (CoT) reasoning. Although CoT has been shown to help in both reference-based and reference-free contexts, the authors question its necessity in cases where verification compares the concluding part of a response to an objective reference answer.

Clarifying whether CoT rationales materially improve semantic equivalence judgments would inform the design of reward modeling and evaluation procedures in RLVR, especially for tasks with free-form answers.

References

While CoT has proven useful in both reference-based~\citep{team2025kimi} and reference-free~\citep{zhang2024generative} settings, it remains an open question how necessary in-depth rationales are for assessing semantic equivalence between reference answers and model responses in the same language, particularly when focusing on the conclusive part of each response.

— Crossing the Reward Bridge: Expanding RL with Verifiable Rewards Across Diverse Domains  (2503.23829 - Su et al., 31 Mar 2025) in Section 7 (Discussions and Conclusions)