aspireai.
PUBLIC EDITION

Existing zero-shot LLM text detectors collapse on instruction-conditioned text, and a new entropy metric called RelPPR reached state-of-the-art black-box detection

AspireAI community · arXiv
Zero-shot detection of machine-generated text matters for misuse, but the two leading detector families, dual-model and resampling-based, work on unprompted continuations and collapse on instruction-conditioned text in the black-box setting where the source model is unknown. The paper diagnoses the two failure modes separately: poor prompt conditioning hurts resampling methods, and diminished cross-model discrepancy hurts dual-model detectors. Its proposed metric starts from an observation that human writing keeps a steady, uniform information flow while machine-generated text has sharp, localized entropy fluctuations, and turns that structural contrast into the Relative Peak Prominence Rate along the entropy trajectory. Evaluated across diverse model families and datasets, RelPPR reaches state-of-the-art black-box detection performance and stays the most reliable detector under practical conditions. The limitation is that it needs repeated sampling from the target model to build the entropy trajectory, so it is not free at inference time.
Read the story and explore more from the AspireAI community.
Discover more stories
Stay curious.
THE BIG PICTURE
A FRESH PERSPECTIVE
Research
One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
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.
Swipe into something new
01 / 1729
The conversation continues
Explore Builds — projects by Kiran Adimatyam ↗
A fresh perspective changes everything.
ASPIREAI — STAY CURIOUS.