Papers › Beyond Masked and Unmasked: Discrete Diffusion Models via Partial Masking

Beyond Masked and Unmasked: Discrete Diffusion Models via Partial Masking

24 May 2025arXiv:2505.18495archive 2025-07-28

Chen-Hao Chao, Wei-Fang Sun, Hanwen Liang, Chun-Yi Lee, Rahul G. Krishnan

Masked diffusion models (MDM) are powerful generative models for discrete data that generate samples by progressively unmasking tokens in a sequence. Each token can take one of two states: masked or unmasked. We observe that token sequences often remain unchanged between consecutive sampling steps; consequently, the model repeatedly processes identical inputs, leading to redundant computation. To address this inefficiency, we propose the Partial masking scheme (Prime), which augments MDM by allowing tokens to take intermediate states interpolated between the masked and unmasked states. This design enables the model to make predictions based on partially observed token information, and facilitates a fine-grained denoising process. We derive a variational training objective and introduce a simple architectural design to accommodate intermediate-state inputs. Our method demonstrates superior performance across a diverse set of generative modeling tasks. On text data, it achieves a perplexity of 15.36 on OpenWebText, outperforming previous MDM (21.52), autoregressive models (17.54), and their hybrid variants (17.58), without relying on an autoregressive formulation. On image data, it attains competitive FID scores of 3.26 on CIFAR-10 and 6.98 on ImageNet-32, comparable to leading continuous generative models.

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Tasks

Image GenerationLanguage Modelling

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Image Generation CIFAR-10 MDM-Prime FID 3.26 #29 of 78 Archive leaderboard report
Image Generation CIFAR-10 MDM-Prime IS 9.67 #29 of 78 Archive leaderboard report
Image Generation CIFAR-10 MDM FID 4.66 #33 of 78 Archive leaderboard report
Image Generation CIFAR-10 MDM IS 9.09 #33 of 78 Archive leaderboard report
Image Generation ImageNet 32x32 MDM-Prime FID 6.98 #6 of 35 Archive leaderboard report
Image Generation ImageNet 32x32 MDM-Prime Inception score 11.65 #6 of 35 Archive leaderboard report
Image Generation ImageNet 32x32 MDM FID 7.91 #7 of 35 Archive leaderboard report
Image Generation ImageNet 32x32 MDM Inception score 11.60 #7 of 35 Archive leaderboard report
Language Modelling OpenWebText MDLM-Prime eval_perplexity 15.36 #1 of 12 Archive leaderboard report
Language Modelling OpenWebText MDLM-Prime parameters 131M #1 of 12 Archive leaderboard report

Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.

Methods

DiffusionSET

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