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Main Authors: Zhu, Yichen, Shi, Xiaoming, Zhao, Peng, Chen, Weiyu, Zhang, Debing, Kwok, James
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.15676
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author Zhu, Yichen
Shi, Xiaoming
Zhao, Peng
Chen, Weiyu
Zhang, Debing
Kwok, James
author_facet Zhu, Yichen
Shi, Xiaoming
Zhao, Peng
Chen, Weiyu
Zhang, Debing
Kwok, James
contents Block discrete diffusion language models factorize a sequence autoregressively over fixed-size positional blocks, decoupling within-block parallel denoising from across-block conditioning. We argue that this rigid partition wastes structure already present in the sequence: blocks defined by position rather than by content separate semantically coherent tokens and group unrelated ones together. We introduce the \textbf{D}ynamic \textbf{C}hunking \textbf{D}iffusion \textbf{M}odel (DCDM), which replaces positional blocks with content-defined semantic chunks. At its core is Chunking Attention, a differentiable layer that routes tokens into $K$ clusters parameterized by learnable subspaces and shaped end-to-end by the diffusion objective. The resulting cluster assignments induce a chunk-causal attention mask under which a discrete diffusion denoiser factorizes the sequence likelihood autoregressively over semantic chunks, strictly generalizing block discrete diffusion. On downstream benchmarks at parameter scales up to 1.5B, DCDM consistently improves over both unstructured and positional-block diffusion baselines, with the advantage stable across scales and visible early in training.
format Preprint
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Dynamic Chunking for Diffusion Language Models
Zhu, Yichen
Shi, Xiaoming
Zhao, Peng
Chen, Weiyu
Zhang, Debing
Kwok, James
Computation and Language
Block discrete diffusion language models factorize a sequence autoregressively over fixed-size positional blocks, decoupling within-block parallel denoising from across-block conditioning. We argue that this rigid partition wastes structure already present in the sequence: blocks defined by position rather than by content separate semantically coherent tokens and group unrelated ones together. We introduce the \textbf{D}ynamic \textbf{C}hunking \textbf{D}iffusion \textbf{M}odel (DCDM), which replaces positional blocks with content-defined semantic chunks. At its core is Chunking Attention, a differentiable layer that routes tokens into $K$ clusters parameterized by learnable subspaces and shaped end-to-end by the diffusion objective. The resulting cluster assignments induce a chunk-causal attention mask under which a discrete diffusion denoiser factorizes the sequence likelihood autoregressively over semantic chunks, strictly generalizing block discrete diffusion. On downstream benchmarks at parameter scales up to 1.5B, DCDM consistently improves over both unstructured and positional-block diffusion baselines, with the advantage stable across scales and visible early in training.
title Dynamic Chunking for Diffusion Language Models
topic Computation and Language
url https://arxiv.org/abs/2605.15676