arXiv AI By Danchun Chen, Qiyao Yan, Chenpeng Wang, Liangming Pan

Towards a Mechanistic Understanding of Propositional Logical Reasoning in Large Language Models

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The paper investigates how large language models perform propositional logical reasoning by conducting a causal mechanistic analysis on the PropLogic-MI benchmark. It identifies four interlocking mechanisms—Staged Computation, Information Transmission, Fact Retrospection, and Specialized Attention Heads—that organize the reasoning process across layers. The study demonstrates that these mechanisms recur across different model families, rule categories, and reasoning hops, indicating a structured, layer‑organized internal process for propositional reasoning.

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