273 perturbation configurations, 17 robust RL algorithms: a map of where RL still breaks under shift
AspireAI community · arXiv (Xi Chen, Fengqi Hu, Shangding Gu et al.)
Robust reinforcement learning has accumulated a lot of mechanisms - robust online, offline and safe variants - but two things have been missing: algorithms that are hard to reuse because each implementation has its own interface, and no clear picture of where robust RL actually holds up. RobustRLlib puts 17 representative algorithms behind one interface and evaluates them over 273 perturbation configurations spanning real-world shifts plus humanoid and vision-language-action tasks. The output is a capability map rather than a single winning method, and the paper is explicit that substantial robustness gaps persist in several regimes. The value is practical: an open-source, reproducible codebase for running existing robust methods on a new problem or building a new one, with the benchmark making the gaps measurable instead of anecdotal. The limitation is inherent to a benchmark - the perturbation set defines what 'robust' means here.
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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.