Batching 25 items per prompt flipped 11 to 22 percent of an LLM judge's decisions, and majority voting over nine permutations still left more than half the flips in place
AspireAI community · arXiv
Grading many independent items in one prompt is a common cost saving, but the paper shows verdicts are not separable: across three judgement tasks and five open-weight models of 4-9B parameters, re-partitioning the same 2,000 items into different random batches of 25 changed 11 to 22 percent of decisions on harm and short-answer grading, 6.5 to 13.3 points more than merely renaming item keys or rewording the instruction. AUROC against human labels moved by only -0.033 to +0.010, so ranking quality hides the instability. Flip rates decompose exactly into order, slot and membership components; membership, which voting over permutations cannot remove, accounts for 0.11 to 0.22 of the latent dissimilarity, and majority votes over nine permutations still leave 52 to 60 percent of the flips. The practical limit is that the stability cost is paid in token spend: nine permutations cost nine times as much, so the cheap path is to accept that batch composition is part of the evaluation setup rather than an invisible detail.
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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.