arXiv Machine Learning

One-Step Next-Latent Prediction Is Not a World Model

arXiv Computer Vision
6d ago

Predictive Latents for Autoregressive Language Models: Possibility, Gauge, and Obstruction

The paper investigates how autoregressive language models can iterate a hidden state without emitting tokens, identifying three distinct risks associated with a latent process: token risk, teacher‑forced latent risk, and open‑loop risk. It shows that when the Bayes next‑token posterior depends on a full‑rank $k$‑dimensional statistic, a width‑$k$ latent with linear least‑squares transition and a refitted unembedding can match the Bayes token predictor, but this match is only up to an invertible gauge. The study also highlights sharp obstructions: a constant latent can drive teacher‑forced risk to zero while token cross‑entropy reverts to marginal entropy, and a perfect token predictor may still conceal a null‑space walk that causes open‑loop error to grow linearly with horizon, indicating that small latent or token losses alone do not guarantee accurate latent rollout without additional rank or injectivity conditions.

By Yuzhou Hong
arXiv Machine Learning
Jul 14

A Control Theory of Predictability in Latent World Models

arXiv:2607. 10362v1 Announce Type: new Abstract: Latent world models are trained to predict future states in a learned representation and are then deployed inside a planner that selects actions by simulating them forward.

By Hanzhe You, Yonggang Zhang, Maohao Ran, Zhiqin Yang, Zhenyuan Zhang, Wei Xue, Jun Song, Xinmei Tian, Yike Guo
arXiv AI
Jun 3

Exact equivariance, kept through training, buys zero-shot generalisation across the symmetry group

arXiv:2606. 03003v1 Announce Type: cross Abstract: A latent world model built from an equivariant encoder $E$ and an equivariant predictor $f$ inherits a provable symmetry of its training loss: when the world's dynamics genuinely carries a group $G$ acting on latents by an orthogonal representation $\rho(g)$, the one-step prediction relMSE is exactly invariant across the whole group, so fitting the dynamics on a restricted slice of orientations mathematically determines it on the entire orbit (j\v{u} y\=i f\v{a}n s\=an).

By Hongbo Wang (Stony Brook University)
arXiv Machine Learning
Oct 15

One-Step Prediction Fidelity Is a Poor Proxy for Planning Performance in JEPA World Models

The paper challenges the common practice of selecting latent world models based on one‑step prediction loss, arguing that this metric poorly predicts planning performance. Using a frozen‑decoder protocol, the authors decompose one‑step error into encoder‑inherent and predictor‑added components and evaluate goal‑conditioned planning across three continuous‑control environments. Their experiments show that improvements in one‑step fidelity do not correlate with planning success, with correlation coefficients near zero and inconsistent exchange rates across tasks.

By Joshua Cheung, Zhang He
arXiv Machine Learning
Aug 27

Rollout-Decoded Reconstruction for Long-Horizon Prediction in Latent World Models

The paper introduces Rollout-Decoded Reconstruction (RDR), a training technique for latent world models that aligns training with evaluation by free-running the model during training, decoding each latent, and penalizing reconstruction error against ground truth. RDR adds a single loss term without extra parameters or significant computational cost, and it reduces to the standard objective when the term weight is zero. In experiments on the chaotic Kuramoto–Sivashinsky equation, RDR improves valid prediction time from 3.87 to 6.97 time units, a 1.80× increase, and the advantage grows with latent width.

By Rishi Shah, Rishav Shrestha