Revisiting Reinforcement Learning for LLM Reasoning from A Cross-Domain Perspective

Zhoujun Cheng1,*, Shibo Hao1,*, Tianyang Liu1,*, Fan Zhou2, Yutao Xie1, Feng Yao1
Yuexin Bian1, Yonghao Zhuang3, Nilabjo Dey4, Yuheng Zha1, Yi Gu1, Kun Zhou1
Yuqi Wang2, Yuan Li3, Richard Fan2, Jianshu She2, Chengqian Gao2, Abulhair Saparov4
Haonan Li2, Taylor W. Killian2, Mikhail Yurochkin2, Zhengzhong Liu2, Eric P. Xing2,3, Zhiting Hu1
1UC San Diego 2MBZUAI 3Carnegie Mellon University 4Purdue University
*Equal Contribution
Figure 1a
Figure 1b

Guru introduces a curated 92K multi-domain RL-for-reasoning dataset and models, enabling a systematic study of cross-domain RL and achieving strong general reasoning performance.

Abstract

Reinforcement learning (RL) has emerged as a promising approach to improve large language model (LLM) reasoning, yet most open efforts focus narrowly on math and code, limiting our understanding of its broader applicability to general reasoning. A key challenge lies in the lack of reliable, scalable RL reward signals across diverse reasoning domains. We introduce Guru, a curated RL reasoning corpus of 92K verifiable examples spanning six reasoning domains—Math, Code, Science, Logic, Simulation, and Tabular—each built through domain-specific reward design, deduplication, and filtering to ensure reliability and effectiveness for RL training. Based on Guru, we systematically revisit established findings in RL for LLM reasoning and observe significant variation across domains. For example, while prior work suggests that RL primarily elicits existing knowledge from pretrained models, our results reveal a more nuanced pattern: domains frequently seen during pretraining (Math, Code, Science) easily benefit from cross-domain RL training, while domains with limited pretraining exposure (Logic, Simulation, Tabular) require in-domain training to achieve meaningful performance gains, suggesting that RL is likely to facilitate genuine skill acquisition. Finally, we present Guru-7B/32B, two models that achieve state-of-the-art performance among open models RL-trained with publicly available data, outperforming best baselines by 7.9% and 6.7% on our 17-task evaluation suite across six reasoning domains. We also show that our models effectively improve the Pass@k performance of their base models, particularly on complex tasks less likely to appear in pretraining data. We release data, models, training and evaluation code to facilitate general-purpose reasoning research at our code repository.

Cross-Domain Reasoning Transfer

To understand how reasoning capabilities generalize with RL, we conducted controlled experiments using Guru. We investigated the impact of RL on single reasoning domains versus a mixed-domain corpus. An experimental dataset, Guru-18K (3K samples from each of the six domains), was used.

Differential Transferability

Analysis of Cross-Domain Reasoning Transfer

Math, Code, and Science benchmarks consistently improved significantly from training on other domains, possibly due to extensive exposure to these tokens during pretraining. Other domains showed limited cross-domain gains. Easier tasks within Math and Code showed positive transfer more readily than challenging benchmarks in the same domains. Mixed-domain training on a uniformly mixed dataset often matched or exceeded single-domain performance.

Reward and Response-Length Dynamics

Reward and Response Length Comparison

In single-domain training, Code, Logic, and Tabular tasks saw contracted outputs, while Science and Math became more verbose. Joint training led to steep reward climbs initially and could reshape length dynamics.

Effects of Training Data Difficulty

Math (in-domain) Code & Tabular (cross-domain)
MATH500 AMC AIME24 HumanEval LiveCodeBench HiTab Multihiertt
75.8 52.1 15.8 82.3 11.1 56.5 32.0
78.6 58.4 21.7 73.1 10.7 53.5 35.5
+2.8 +6.3 +5.9 △ (+/-) -9.2 -0.4 -3.0 +3.5

Training on harder math data improved in-domain math performance but could degrade performance on easier cross-domain tasks. For beneficial cross-domain transfer, a balanced distribution of difficulties or explicit inclusion of cross-domain data may be more effective.

Data Construction

1
Data Sourcing — Curating datasets across Math, Code, Science, Logic, Simulation, and Tabular domains
2
Deduplication — Removing overlapping content via substring matching (27.2% Math, 7.5% Code reduction)
3
Reward Design — Domain-specific verification: rule-based, execution-based, and model-based
4
Heuristic Filtering — Removing noise and controlling complexity with uniform sampling
5
Difficulty Filtering — Selecting samples based on model performance gaps for appropriate challenge levels
Final Result: 92K curated examples

Experiment Results

We trained 7B and 32B models on the full Guru dataset to demonstrate the practical impact of multi-domain data. We used verl as the RL training framework and GRPO as the algorithm. The 7B model was trained for 2 epochs on 4 nodes (8 Hopper GPUs each) and the 32B model on 16 nodes for 2 epochs.

Domain Benchmarks 7B 32B
Guru 7B General Reasoner 7B ORZ 7B SimpleRL 7B Guru 32B ORZ 32B SimpleRL 32B
Math AIME24(avg@32)17.5017.0816.2515.6034.8947.5027.20
MATH50077.2570.4080.8087.0086.0089.8089.60
Code LiveCodeBench(avg@4)16.498.515.476.7229.3022.0419.80
HumanEval(avg@4)82.6261.1267.3858.0890.8584.3081.25
MBPP70.0039.8048.4049.6078.8074.2076.75
Science GPQA-diamond(avg@4)40.7838.6437.6335.9850.6355.6746.46
SuperGPQA31.8030.6429.7527.2943.6046.0537.73
Logic ARC-AGI(avg@4)3.310.750.000.507.632.315.25
Zebra Puzzle(avg@4)39.400.071.000.6245.210.541.16
Simulation CodeI/O(avg@4)15.637.135.136.6312.633.759.75
CruxEval-I61.7263.6369.3856.2580.6371.1372.63
CruxEval-O71.2856.5065.8858.3188.7582.3867.75
Tabular FinQA34.7034.3337.6035.1046.1445.2045.41
HiTab74.2054.4054.1050.4082.0063.3069.00
MultiHiertt(avg@4)44.9431.6238.1037.5755.2852.8352.83
Others IFEval35.8139.5632.7236.6955.4538.2655.27
LiveBench18.5719.7612.6415.2034.3028.7828.33
Average Score43.2933.7635.4233.9754.2447.5346.25

Pass@k Curves

Pass@k Comparison
Top Model Comparison

Pass@k behavior is highly task-dependent: while improvements in math tasks (e.g., AIME) might largely leverage base model capabilities, tasks like Zebra Puzzle demonstrate genuine reasoning expansion. Model scale also matters—larger models (32B) show more consistent gains than smaller ones (7B). Additionally, decoding hyperparameters significantly affect Pass@k, with higher temperature and top-p enhancing exploration and performance at larger k. These insights suggest Pass@k reflects both model and sampling dynamics, and should be interpreted cautiously.

BibTeX

@misc{cheng2025revisiting,
      title         = {Revisiting Reinforcement Learning for LLM Reasoning from A Cross-Domain Perspective},
      author        = {Zhoujun Cheng and Shibo Hao and Tianyang Liu and Fan Zhou and Yutao Xie and Feng Yao and Yuexin Bian and Yonghao Zhuang and Nilabjo Dey and Yuheng Zha and Yi Gu and Kun Zhou and Yuqi Wang and Yuan Li and Richard Fan and Jianshu She and Chengqian Gao and Abulhair Saparov and Haonan Li and Taylor W. Killian and Mikhail Yurochkin and Zhengzhong Liu and Eric P. Xing and Zhiting Hu},
      journal       = {arXiv preprint arXiv:2506.14965},
      year          = {2025},
      doi           = {10.48550/arXiv.2506.14965},
      url           = {https://arxiv.org/abs/2506.14965}
    }