A reward function written for one Overcooked kitchen transferred unchanged to layouts it had never seen
AspireAI community · arXiv (Dogan Urgun)
Cooperative multi-agent reinforcement learning depends heavily on a reward function that usually has to be hand-designed again every time the environment or the team changes, and LLM-written rewards tend to be designed and tested in a single setting. GARDEN develops one reward program for a family of related scenarios and transfers it unchanged to scenarios that were unavailable during its design, with an LLM reward engineer investigating environment code, training records and agent behavior and testing draft rewards in trial training runs while the learning algorithm and the final-selection rule stay fixed. On unseen Overcooked and SMAX scenarios, task returns rose 58.2 percent and 52.5 percent over the default rewards on two kitchen layouts, and mean win rate in two combat scenarios went from 51.0 percent to 89.9 percent, beating fixed diagnostic feedback methods that reached 84.2 and 79.2 percent under matched candidate and probe budgets.
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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.