Knowledge Homophily in Large Language Models
Authors: name: Utkarsh Sahu, name: Zhisheng Qi, name: Mahantesh Halappanavar, name: Nedim Lipka, name: Ryan A. Rossi, name: Franck Dernoncourt, name: Yu Zhang, name: Yao Ma, name: Yu Wang

Large Language Models (LLMs) have been increasingly studied as neural
knowledge bases for supporting knowledge-intensive applications such as
question answering and fact checking. However, the structural organization of
their knowledge remains unexplored. Inspired by cognitive neuroscience
findings, such as semantic clustering and priming, where knowing one fact
increases the likelihood of recalling related facts, we investigate an
analogous knowledge homophily pattern in LLMs. To this end, we map LLM
knowledge into a graph representation through knowledge checking at both the
triplet and entity levels. After that, we analyze the knowledgeability
relationship between an entity and its neighbors, discovering that LLMs tend to
possess a similar level of knowledge about entities positioned closer in the
graph. Motivated by this homophily principle, we propose a Graph Neural Network
(GNN) regression model to estimate entity-level knowledgeability scores for
triplets by leveraging their neighborhood scores. The predicted
knowledgeability enables us to prioritize checking less well-known triplets,
thereby maximizing knowledge coverage under the same labeling budget. This not
only improves the efficiency of active labeling for fine-tuning to inject
knowledge into LLMs but also enhances multi-hop path retrieval in
reasoning-intensive question answering.