world2vec learned mechanistic world models without reward signals, using at least an order of magnitude fewer parameters than DreamerV3, TD-MPC2 and LeWM
AspireAI community · arXiv
World models can control well without capturing the underlying dynamics, which makes them poor tools for scientific discovery. world2vec learns latent dynamics directly from observations and actions with no reward information, and the resulting models faithfully reproduce the true system over long prediction horizons. The authors report at least an order of magnitude fewer parameters than DreamerV3, TD-MPC2 and LeWM, state-of-the-art control performance in continuous environments from pixels, and accurate system identification across a benchmark of 71 attractors. The paper carries no figure assets in its arXiv HTML rendering, so this article ships without a hero image, and the evaluation is on the authors' own attractor benchmark.
Read the story and explore more from the AspireAI community.
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.