SKIntern: Internalizing Symbolic Knowledge for Distilling Better CoT Capabilities into Small Language Models
Paper · 2025 · Huanxuan Liao, Shizhu He, Yupu Hao et al.
Summary
Small language models (SLMs) are cheaper and more private than LLMs, but they reason less well. Earlier CoT distillation methods such as KARD and CasCoD add retrieved documents or multi-step generation to help them. That extra input makes inference slower and can bring in irrelevant or misleading content. SKIntern tackles this by teaching the student model to absorb the helper material during training, so it is not needed at test time.
A teacher LLM first produces filtered rationales plus two kinds of symbolic knowledge: learning summaries and supplementary material. The most relevant items are chosen by cosine similarity. During progressive fine-tuning, a linear decay schedule (a form of curriculum learning) gradually shrinks this knowledge at the token level and prunes few-shot examples. By the end, the model answers from the question alone.
Tested on TinyLLaMA and LLaMA2-7B across factual, math and general reasoning benchmarks, SKIntern beats strong baselines by over 5% in both in-domain and out-of-domain settings. It also cuts inference FLOPs by up to 4×, which suits cost-sensitive deployment.
Key points
- Baselines compared include Std-CoT, KARD (retrieval-augmented) and CasCoD (cascaded rationale generation and use). Evaluation covers 7 reasoning benchmarks, including BBH, BB, AGIEval, GSM8K+ and ARC-E.
- On LLaMA2-7B, SKIntern scores 69.3 on BBH, 37.2 on BB, 31.3 on AGIEval, 21.2 on GSM8K+ and 78.1 on ARC-E.
- Among the schedule shapes tested (linear, exponential, inverse exponential), linear decay worked best. With 12 training epochs, the best number of schedule steps was T=4 (BBH 69.3, compared with 60.2 at T=3).
- Ablations show that each component matters. Removing learning summaries, supplementary knowledge or example pruning lowers results, for example BBH falls to 59.8, 62.3 and 61.9 respectively.
- The authors list two limitations: training is more complex and expensive, and generating the symbolic knowledge requires paid LLM API calls. Code is announced at github.com/Xnhyacinth/SKIntern.
Fields, topics and concepts
📚 Shelves 2The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 works
🧭 Topics 1Research subjects and languages the work is about.Language models & pretraining · 3,320 works
Cite
Cite as Huanxuan Liao, Shizhu He, Yupu Hao, Xiang Li, Yuanzhe Zhang, Jun Zhao and Kang Liu. 2025. SKIntern: Internalizing Symbolic Knowledge for Distilling Better CoT Capabilities into Small Language Models. Proceedings of the 31st International Conference on Computational Linguistics.
@inproceedings{liao2025skintern,
title = {{SKIntern: Internalizing Symbolic Knowledge for Distilling Better CoT Capabilities into Small Language Models}},
author = {Huanxuan Liao, Shizhu He, Yupu Hao, Xiang Li, Yuanzhe Zhang, Jun Zhao and Kang Liu},
booktitle = {Proceedings of the 31st International Conference on Computational Linguistics},
year = {2025},
url = {https://aclanthology.org/2025.coling-main.215/}
}References
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