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Knowledge Graph-Enhanced Long-CoT for Complex Biomolecular Reasoning

Aug 2026 · Proceedings of the 32nd ACM SIGKDD Conference on Knowledge Discovery and Data Mining V.2 · 0 citations · 9 references

TL;DR

Results validate that KG-guided reasoning serves as a critical mechanism to compensate for parameter disparity, particularly in tasks requiring deep traversal of biological mechanisms.

Abstract

Biomolecular scientific questions often require multi-step mechanistic reasoning over structured knowledge such as protein–protein interactions, pathways, and disease associations. While large language models (LLMs) can generate chain-of-thought (CoT) rationales, biomolecular CoT is frequently unreliable due to biologically implausible steps and long-horizon inconsistencies, and naive knowledge augmentation remains brittle on large, noisy knowledge graphs. We propose Bio-KCoT, a knowledge-augmented long-CoT framework that emphasizes principled use of structured knowledge. Bio-KCoT transforms knowledge graphs (KGs) into high-fidelity mechanistic reasoning trajectories. Instead of relying on naive shortest paths or direct KG prompting, Bio-KCoT adopts a generative paradigm that synthesizes mechanistic explanations anchored on KG entities and distills them into structured reasoning topologies. These curated chains serve as high-quality target trajectories during Supervised Fine-Tuning (SFT), enabling the model to learn structured mechanistic decomposition. Subsequently, to further enforce logical rigor, we apply Group Relative Policy Optimization (GRPO) with a KG-aligned process reward. This mechanism explicitly scores intermediate steps against the curated evidence, penalizing unsupported hops and reducing hallucinations even when the final answer is correct. To rigorously evaluate these capabilities, we construct BioMolKGQA, a benchmark with curated multi-hop evidence paths spanning diverse biomolecular QA pairs and reasoning depths. Extensive experiments on this dataset confirm that Bio-KCoT delivers substantial performance gains, enabling parameter-constrained models to rival the reasoning fidelity of significantly larger baselines. These results validate that KG-guided reasoning serves as a critical mechanism to compensate for parameter disparity, particularly in tasks requiring deep traversal of biological mechanisms.

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