UPenn paper unifies diffusion and autoregression on one corruption lattice to predict decoding costs

upenn · hf · 2026-10-10

A UPenn team frames diffusion, autoregressive, and hybrid generative models as paths on a single corruption lattice, defining a schedule's cost as the dependence discarded by its parallel steps. They show the minimum steps of a zero-cost schedule are set by data geometry: for Markov-on-graph data, it equals the graph's treedepth (logarithmic in sequence length, linear in grid side length). Schedules below this bound pay positive cost, and the authors predict schedule rankings before decoding using a pairwise-dependence kernel estimated from pretrained weights, verified across text, image, and video generation. The work offers a unified design principle for future AR and diffusion models; code is open-sourced.

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