Integrated and Cross-Architecture Interpretation of LLM Reasoning

Leonardo Matthew Yauw, Wei-Bin Kou, Yujiu Yang


Abstract
Understanding how LLMs reason is hindered by a practical asymmetry: while their generated outputs are observable, the underlying reasoning patterns remain opaque. Relying on single probes, such as Mutual Information Peak (MIP) or Deep-Thinking Ratio (DTR), risks underestimating the genuine inferential structure. To response this deficiency, we present an Integrated, cross-Architecture Reasoning (IAR) framework, designed to provide a unified approach to LLM reasoning interpretability. Specifically, we first propose to use bandwidth-calibrated MIP coupled with Tukey IQR peak-detection to isolate reasoning-crucial tokens at the output layer. Second, we performed an overlap analysis between MIP-picked tokens and DTR-deep tokens to trace the cross-layer trajectories of those tokens. This also discloses whether reasoning-crucial tokens are computation-intensive as well, further facilitating to understand how reasoning patterns evolve across model layers. Finally, we apply a Jaccard stability metric over multi-domain problems to verify if the MIP-identified tokens are reasoning quality-guaranteed. Extensive experiments on six models across four domains (mathematics, code, logic, and common sense) demonstrate IAR’s generalizable interpretation capabilities across architectures. Our code is available at https://github.com/LeonardoMatthew/IAR.
Anthology ID:
2026.emnlp-main.803
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
18691–18718
Language:
URL:
https://aclanthology.org/2026.emnlp-main.803/
DOI:
Bibkey:
Cite (ACL):
Leonardo Matthew Yauw, Wei-Bin Kou, and Yujiu Yang. 2026. Integrated and Cross-Architecture Interpretation of LLM Reasoning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 18691–18718, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Integrated and Cross-Architecture Interpretation of LLM Reasoning (Yauw et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.803.pdf