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arXiv · 2606.02237

Why Are DMD Students Lazy? Understanding the Copying Behavior in Few-Step Distillation

Shucheng Li·Iolo Jones·Alexander Tong·Michael M. Bronstein
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Abstract

Distribution Matching Distillation (DMD) compresses pretrained diffusion models into efficient few-step generators by aligning their noised distributions across all scales. In principle, such distribution-level supervision remains agnostic to specific noise-data pairings of the teacher; this provides the student the freedom to remap latent noise, a behavior consistently observed in low-dimensional settings. Surprisingly, we find that in high-dimensional settings, distilled students spontaneously reproduce the original noise-data pairings of the teacher, a phenomenon we term copying. We demonstrate that copying is neither a byproduct of adversarial objectives nor a result of teacher memorization. Instead, our evidence suggests that copying is an emergent property arising from the limited geometric freedom of the student model during high-dimensional distillation.

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Shucheng Li, Iolo Jones, Alexander Tong, Michael M. Bronstein. 2026-06-01. Why Are DMD Students Lazy? Understanding the Copying Behavior in Few-Step Distillation. https://arxiv.org/abs/2606.02237

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