PaCoRe: Learning to Scale Test-Time Compute with Parallel Coordinated Reasoning

📖 Overview

We introduce PaCoRe (Parallel Coordinated Reasoning), a framework that shifts the driver of inference from sequential depth to coordinated parallel breadth, breaking the model context limitation and massively scaling test time compute:

• Think in Parallel: PaCoRe launches massive parallel exploration trajectories.
• Coordinate in Multi-rounds: It employs a message-passing architecture to compact these thoughts into concise messages and synthesize them to guide the next round.

Trained via large-scale, outcome-based reinforcement learning, PaCoRe masters the Reasoning Synthesis capabilities required to reconcile diverse parallel insights.

The approach yields strong improvements across diverse domains, and notably pushes reasoning beyond frontier systems in mathematics: an 8B model reaches 94.5% on HMMT 2025, surpassing GPT-5’s 93.2% by scaling effective TTC to roughly two million tokens.

We open-source model checkpoints, training data, and the full inference pipeline to accelerate follow-up work!

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Figure 1 | Parallel Coordinated Reasoning (PaCoRe) performance. Left: On HMMT 2025, PaCoRe-8B demonstrates remarkable test-time scaling, yielding steady gains and ultimately surpassing GPT-5. Right: On LiveCodeBench, the RLVR-8B model fails to leverage increased test-time compute, while PaCoRe-8B model effectively unlocks substantial gains as the test-time compute increases.

Figure 2 | PaCoRe Training dynamics. Left panels: The Training Reward and Response Length steadily increase, demonstrating the training stability and effectiveness. Right panels: Evaluation on HMMT 2025 and LiveCodeBench (2408-2505). Performance is reported using single round coordinated reasoning in PaCoRe inference setting with $\vec{K} = [16]$.

🔥 Releases

[2025/12/09] We are excited to release the PaCoRe-8B ecosystem:

• 📝 In-depth Technical Report: PaCoRe: Learning to Scale Test-Time Compute with Parallel Coordinated Reasoning.
• 🤖 Model:
  • PaCoRe-8B: Our final PaCoRe-trained model checkpoint!
  • RLVR-8B-0926: The initial checkpoint of our study, conducted strong reasoning-oriented post-trained on Qwen3-8B-Base.
• 📚 Data: PaCoRe-Train-8k The high-quality training corpus, including opensource_math, public_mathcontest, synthetic_math and code:
  • 🤗 Stage1-3k: PaCoRe-Train-Stage1-3k
  • 🤗 Stage2-5k: PaCoRe-Train-Stage2-5k

🔍 Experiments

Table 1 | For each benchmark, we report accuracy together with total TTC (in thousands). For Low, Medium, and High, we apply the inference trajectory configuration as $\vec{K}=[4]$, $[16]$, and $[32, 4]$ separately.

Key Findings

• Message Passing Unlocks Scaling. Without compaction, performance flatlines at the context limit. PaCoRe breaks the memory barrier and lets reasoning scale freely.
• Breadth > Depth. All compute is not equal. Coordinated parallel reasoning delivers far higher returns than extending a single chain.
• Data as a Force Multiplier. The PaCoRe corpus provides exceptionally valuable supervision—even baseline models see substantial gains when trained on it.

Getting Started 🚀

Installation

First, install the package from the official repository:

pip install -e . 

Model Serving

You can directly use vllm serve to serve the model:

vllm serve stepfun-ai/PaCoRe-8B

Inference Example

Next, you can run our example inference code with PaCoRe-low inference setting:

python playground/example_batch_inference_pacore_low_1210.py

🙏 Acknowledgements

• This work was supported by computing resources and infrastructure provided by StepFun and Tsinghua University.
• We are built on amazing open source models and data; thanks again!

📜 Citation

@misc{pacore2025,
      title={PaCoRe: Learning to Scale Test-Time Compute with Parallel Coordinated Reasoning}, 
      author={Jingcheng Hu and Yinmin Zhang and Shijie Shang and Xiaobo Yang and Yue Peng and Zhewei Huang and Hebin Zhou and Xin Wu and Jie Cheng and Fanqi Wan and Xiangwen Kong and Chengyuan Yao and Kaiwen Yan and Ailin Huang and Hongyu Zhou and Qi Han and Zheng Ge and Daxin Jiang and Xiangyu Zhang and Heung-Yeung Shum},
      year={2026},
      eprint={2601.05593},
      archivePrefix={arXiv},
      primaryClass={cs.LG},
      url={https://arxiv.org/abs/2601.05593}, 
}