CHORD detected hallucinations across models it never trained on by treating hidden states as relational graphs over layers, tokens and features
AspireAI community · arXiv (NeurIPS 2026 Spotlight)
Hallucination detectors built on internal representations are usually model-specific and fail to transfer to LLMs they have never seen, because hidden states from different models are semantically inconsistent with one another. CHORD argues that the relational structure over layers, tokens and features carries the transferable signal even when the semantics do not, representing hidden states as joint relational graphs, feeding them through relation-aware attention and using meta-learning to shape the features toward transferable detection signals. The authors report that CHORD outperforms representative detection methods in cross-model generalization, and the paper was accepted to NeurIPS 2026 as a Spotlight paper. The abstract carries no headline metric for that comparison, so treat the outperformance claim as the authors' own and read the 64-page paper for the per-model numbers.
Read the story and explore more from the AspireAI community.
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.