Revise, Don't Freeze: Sampler-Matched Training for Self-Correcting Masked Diffusion Language Models

Fuente: arXiv
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Hauptverfasser: Yu, Longxuan, Zhang, Shaorong, Fu, Yu, Liu, Hui, Dong, Yue, Steeg, Greg Ver
Format: Preprint
Veröffentlicht: 2026
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author Yu, Longxuan
Zhang, Shaorong
Fu, Yu
Liu, Hui
Dong, Yue
Steeg, Greg Ver
author_facet Yu, Longxuan
Zhang, Shaorong
Fu, Yu
Liu, Hui
Dong, Yue
Steeg, Greg Ver
contents Masked diffusion language models (MDLMs) re-predict every position at each denoising step, but standard samplers commit tokens once revealed, leaving this revision capability unused. Existing approaches either add heuristic or learned mechanisms to revise committed tokens, or remask them back to [MASK] before re-predicting; a principled sampler that directly revises visible tokens without auxiliary modules remains underexplored. We introduce D3IM, a parameter-free sampler derived as a corrector-style reverse update that permits direct visible-to-visible revision without additional modules or auxiliary passes. D3IM also reveals a model-side obstacle we term preservation bias: the model tends to reproduce its own wrong committed tokens rather than correct them. We address this with SCOPE (Self-Conditioned On Prediction Errors), a lightweight post-training procedure that simulates D3IM's sampling process. On LLaDA-8B at 64 denoising steps, SCOPE+D3IM improves over the original LLaDA-8B with standard unmasking by +13.0 on GSM8K (68.3%), +4.8 on MATH-500 (23.6%), +15.3 on HumanEval (29.3%), and +10.4 on MBPP (30.8%), with gains that increase as more denoising steps are used on math and HumanEval.
format Preprint
id arxiv_https___arxiv_org_abs_2606_01026
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Revise, Don't Freeze: Sampler-Matched Training for Self-Correcting Masked Diffusion Language Models
Yu, Longxuan
Zhang, Shaorong
Fu, Yu
Liu, Hui
Dong, Yue
Steeg, Greg Ver
Computation and Language
Masked diffusion language models (MDLMs) re-predict every position at each denoising step, but standard samplers commit tokens once revealed, leaving this revision capability unused. Existing approaches either add heuristic or learned mechanisms to revise committed tokens, or remask them back to [MASK] before re-predicting; a principled sampler that directly revises visible tokens without auxiliary modules remains underexplored. We introduce D3IM, a parameter-free sampler derived as a corrector-style reverse update that permits direct visible-to-visible revision without additional modules or auxiliary passes. D3IM also reveals a model-side obstacle we term preservation bias: the model tends to reproduce its own wrong committed tokens rather than correct them. We address this with SCOPE (Self-Conditioned On Prediction Errors), a lightweight post-training procedure that simulates D3IM's sampling process. On LLaDA-8B at 64 denoising steps, SCOPE+D3IM improves over the original LLaDA-8B with standard unmasking by +13.0 on GSM8K (68.3%), +4.8 on MATH-500 (23.6%), +15.3 on HumanEval (29.3%), and +10.4 on MBPP (30.8%), with gains that increase as more denoising steps are used on math and HumanEval.
title Revise, Don't Freeze: Sampler-Matched Training for Self-Correcting Masked Diffusion Language Models
topic Computation and Language
url https://arxiv.org/abs/2606.01026