Comparing language models on energy per successfully completed task, not per call, found a 3B model used a tenth the energy of a 27B model at 20 steps while a 1.7B model used nearly four times as much as an 8B one at 100 steps
AspireAI community · arXiv
For agents that plan and act over many steps, comparing models per API call misleads: a task only succeeds if every step succeeds, and failed attempts still burn resources. This paper frames model selection as a multi-criteria decision problem over resources per successfully completed task and derives crossover task lengths at which two models swap their efficiency ranking, each objective having its own crossover. Below the shortest crossover the less reliable model dominates, above the longest the more reliable one does, and in between both are Pareto-efficient. In a pilot with 15 open-weight models on two synthetic agent tasks with measured GPU energy, the predicted crossover fell inside the observed range for 72 of 88 observed crossovers. The concrete result is that smaller is greener only up to a task length that can be predicted, not unconditionally. The limitation is that the pilot is small and synthetic, with two tasks and a measured rather than modelled energy budget.
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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.