SOD-1.7B / README.md
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metadata
language:
  - en
license: apache-2.0
library_name: transformers
base_model: Qwen/Qwen3-1.7B
tags:
  - agent
  - tool-use
  - distillation
  - math
  - code
  - reasoning
pipeline_tag: text-generation

SOD-1.7B

Paper on arXiv Code on GitHub HuggingFace Collection

About

SOD-1.7B is a 1.7B student model distilled from a 4B teacher using SOD (Step-wise On-policy Distillation), a method designed for training small language model agents with tool-integrated reasoning capabilities.

SOD addresses the cascading error propagation problem in on-policy distillation for agentic reasoning by introducing an adaptive step-level weighting mechanism that suppresses distillation loss on drifted steps and restores supervision when the student recovers alignment โ€” all at negligible additional computational cost.

Model Information

Attribute Value
Base Model Qwen3-1.7B
Teacher Model SOD-GRPO_teacher-4B
Training Pipeline Cold-Start SFT โ†’ SOD (Step-wise On-policy Distillation)
Parameters 1.7B

Related Models

Model Description
SOD-0.6B SOD-distilled 0.6B student
SOD-1.7B SOD-distilled 1.7B student (this model)
SOD-GRPO_teacher-4B GRPO-trained 4B teacher model

Performance

We report average@32 over 5 runs on challenging math, science, and code benchmarks.

1.7B Student Results

Method AIME 2024 AIME 2025 GPQA-Diamond LiveCodeBench-v6 Average
Vanilla 9.90 8.96 26.80 22.73 17.10
SFT 26.77 22.40 29.85 24.63 25.91
GRPO 25.63 21.67 33.55 20.70 25.39
OPD 43.86 37.04 31.73 32.45 36.27
OPSD_gt 33.85 24.69 35.02 22.73 29.07
OPSD_hint 34.42 21.43 33.46 23.12 28.11
SOD (This Model) 50.83 41.72 38.72 40.63 42.98

Teacher Model (4B)

Method AIME 2024 AIME 2025 GPQA-Diamond LiveCodeBench-v6 Average
GRPO 67.60 60.42 55.19 63.13 61.59

Key Highlights

  • ๐Ÿ† Recovers 69.8% of teacher performance with only 1.7B parameters (42.98 vs 61.59)
  • ๐Ÿ“ˆ +18.5% over second-best baseline (OPD) on average
  • ๐Ÿ’ก Minimal extra compute: The divergence metric reuses log-probabilities already computed in the forward pass

Citation

@article{zhong2026sod,
      title={SOD: Step-wise On-policy Distillation for Small Language Model Agents}, 
      author={Qiyong Zhong and Mao Zheng and Mingyang Song and Xin Lin and Jie Sun and Houcheng Jiang and Xiang Wang and Junfeng Fang},
      journal={arXiv preprint arXiv:2605.07725},
      year={2026}
}