Reinforcement learning with verifiable rewards (RLVR) has emerged as a powerful paradigm for improving the reasoning capabilities of LLMs. However, the role of supervised fine-tuning (SFT) data in enabling effective downstream RL remains underexplored. In this paper, we investigate a key hypothesis: the diversity of reasoning steps in chain-of-thought (CoT) during SFT is a critical enabler of RLVR performance. To test this hypothesis, we introduce EquivAug, a data augmentation framework that uses symbolic equivalence transformations to generate diverse yet provably correct reasoning paths. By converting CoT solutions into formal symbolic representations, applying equivalence transformations, and reconstructing natural-language explanations, EquivAug produces training data that differs in reasoning steps rather than surface-level lexical variation. Experiments on GSM8K and FOLIO across model scales demonstrate that EquivAug consistently achieves the highest reasoning path diversity after SFT and the strongest accuracy after GRPO. Our results establish that CoT diversity during SFT is positively correlated with downstream RLVR performance.
Figures & tables
Figure 1: Overview of our pipeline. Left: The EquivAug data augmentation framework converts chain-of-thought solutions into symbolic representation, applies equivalence transformation rules to generate structurally diverse yet semantically equivalent variants verified by a symbolic solver, and reconstructs them back into natural language. Right: The augmented data is used for supervised fine-tuning, followed by reinforcement learning with GRPO.
Figure 2: Effect of transformation complexity on performance (GSM8K on Qwen2.5-1.5B).
Figure 3: Out-of-distribution performance of different data augmentation methods on MATH500 and SVAMP.
Appendix figures & tables2 assets
Supplementary material from the paper’s appendix.
Appendix
Figure 4: Test accuracy for different models during GRPO training for GSM8K on Llama3.1-8B.
Figure 5: Entropy of different models during GRPO training for folio on Llama3.1-8B.
Beijing Advanced Innovation Center for Future Blockchain and Privacy Computing, Beihang University · School of Artificial Intelligence, Beihang University