arXiv Machine Learning By Zongye Lyu

Same Answer, New Box: How Much of RLVR's Out-of-Domain Gain Is Answer Format?

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The paper investigates whether the reported out‑of‑domain performance gains of Reinforcement Learning with Verifiable Rewards (RLVR) are due to improved answer quality or simply to changes in answer formatting. By comparing scores from standard extractors with a custom extractor that distinguishes answers inside a oxed{} notation, the authors find that a large portion (about 82%) of the apparent gains on 7B SimpleRL models vanish, indicating that the gains are largely due to formatting rather than better answers. In contrast, a 32B model trained with a different recipe shows minimal format‑related gains, suggesting that the effect depends on the training setup.

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