Sequential Diffusion Language Models

Fuente: arXiv
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Main Authors: Liu, Yangzhou, Cao, Yue, Li, Hao, Luo, Gen, Chen, Zhe, Wang, Weiyun, Liang, Xiaobo, Qi, Biqing, Wu, Lijun, Tian, Changyao, Zhang, Yanting, Li, Yuqiang, Lu, Tong, Qiao, Yu, Dai, Jifeng, Wang, Wenhai
Format: Preprint
Published: 2025
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author Liu, Yangzhou
Cao, Yue
Li, Hao
Luo, Gen
Chen, Zhe
Wang, Weiyun
Liang, Xiaobo
Qi, Biqing
Wu, Lijun
Tian, Changyao
Zhang, Yanting
Li, Yuqiang
Lu, Tong
Qiao, Yu
Dai, Jifeng
Wang, Wenhai
author_facet Liu, Yangzhou
Cao, Yue
Li, Hao
Luo, Gen
Chen, Zhe
Wang, Weiyun
Liang, Xiaobo
Qi, Biqing
Wu, Lijun
Tian, Changyao
Zhang, Yanting
Li, Yuqiang
Lu, Tong
Qiao, Yu
Dai, Jifeng
Wang, Wenhai
contents Diffusion language models (DLMs) have strong theoretical efficiency but are limited by fixed-length decoding and incompatibility with key-value (KV) caches. Block diffusion mitigates these issues, yet still enforces a fixed block size and requires expensive training. We introduce Next Sequence Prediction (NSP), which unifies next-token and next-block prediction, enabling the model to adaptively determine the generation length at each step. When the length is fixed to 1, NSP reduces to standard next-token prediction. Building on NSP, we propose Sequential Diffusion Language Model (SDLM), which can retrofit pre-trained autoregressive language models (ALMs) at minimal cost. Specifically, SDLM performs diffusion inference within fixed-size mask blocks, but dynamically decodes consecutive subsequences based on model confidence, thereby preserving KV-cache compatibility and improving robustness to varying uncertainty and semantics across the sequence. Experiments show that SDLM matches or surpasses strong autoregressive baselines using only 3.5M training samples, while achieving 2.1 higher throughput than Qwen-2.5. Notably, the SDLM-32B model delivers even more pronounced efficiency gains, demonstrating the strong scalability potential of our modeling paradigm. Project page and codes: https://github.com/OpenGVLab/SDLM
format Preprint
id arxiv_https___arxiv_org_abs_2509_24007
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sequential Diffusion Language Models
Liu, Yangzhou
Cao, Yue
Li, Hao
Luo, Gen
Chen, Zhe
Wang, Weiyun
Liang, Xiaobo
Qi, Biqing
Wu, Lijun
Tian, Changyao
Zhang, Yanting
Li, Yuqiang
Lu, Tong
Qiao, Yu
Dai, Jifeng
Wang, Wenhai
Computation and Language
Machine Learning
Diffusion language models (DLMs) have strong theoretical efficiency but are limited by fixed-length decoding and incompatibility with key-value (KV) caches. Block diffusion mitigates these issues, yet still enforces a fixed block size and requires expensive training. We introduce Next Sequence Prediction (NSP), which unifies next-token and next-block prediction, enabling the model to adaptively determine the generation length at each step. When the length is fixed to 1, NSP reduces to standard next-token prediction. Building on NSP, we propose Sequential Diffusion Language Model (SDLM), which can retrofit pre-trained autoregressive language models (ALMs) at minimal cost. Specifically, SDLM performs diffusion inference within fixed-size mask blocks, but dynamically decodes consecutive subsequences based on model confidence, thereby preserving KV-cache compatibility and improving robustness to varying uncertainty and semantics across the sequence. Experiments show that SDLM matches or surpasses strong autoregressive baselines using only 3.5M training samples, while achieving 2.1 higher throughput than Qwen-2.5. Notably, the SDLM-32B model delivers even more pronounced efficiency gains, demonstrating the strong scalability potential of our modeling paradigm. Project page and codes: https://github.com/OpenGVLab/SDLM
title Sequential Diffusion Language Models
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2509.24007