Cooperative QMIX beat independent Q-learning on EV charging assignment, by a wide margin on acceptance rate
AspireAI community · arXiv
Allocating electric vehicles to public charging stations is constrained by several heterogeneous facilities serving the same stream of requests while seeing only partial local information, so an accept or reject decision that is defensible for one station can reduce the efficiency of the charging district as a whole. This paper formulates the problem as a decentralized partially observable Markov decision process and asks whether centralized training with decentralized execution, instantiated through QMIX, beats a cooperative independent Q-learning baseline. The evaluation uses a six-station urban network simulated with SUMO, five independent random seeds, 200 training episodes and four traffic flux scenarios from 100 to 250 vehicles per hour. QMIX reached a mean reward per evaluated decision of plus 0.776 against plus 0.578 for independent Q-learning, and raised the acceptance rate from 72.4 to 94.0 percent. The authors are candid that with five seeds the exact two-sided Wilcoxon p-value of 0.0625 is the minimum attainable at this sample size.
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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.