Characterizing Memorization in Diffusion Language Models: Generalized Extraction and Sampling Effects

Fuente: arXiv
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Autores principales: Luo, Xiaoyu, Yu, Wenrui, Li, Qiongxiu, Bjerva, Johannes
Formato: Preprint
Publicado: 2026
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author Luo, Xiaoyu
Yu, Wenrui
Li, Qiongxiu
Bjerva, Johannes
author_facet Luo, Xiaoyu
Yu, Wenrui
Li, Qiongxiu
Bjerva, Johannes
contents Autoregressive language models (ARMs) have been shown to memorize and occasionally reproduce training data verbatim, raising concerns about privacy and copyright liability. Diffusion language models (DLMs) have recently emerged as a competitive alternative, yet their memorization behavior remains largely unexplored due to fundamental differences in generation dynamics. To address this gap, we present a systematic theoretical and empirical characterization of memorization in DLMs. We propose a generalized probabilistic extraction framework that unifies prefix-conditioned decoding and diffusion-based generation under arbitrary masking patterns and stochastic sampling trajectories. Theorem 4.3 establishes a monotonic relationship between sampling resolution and memorization: increasing resolution strictly increases the probability of exact training data extraction, implying that autoregressive decoding corresponds to a limiting case of diffusion-based generation by setting the sampling resolution maximal. Extensive experiments across model scales and sampling strategies validate our theoretical predictions. Under aligned prefix-conditioned evaluations, we further demonstrate that DLMs exhibit substantially lower memorization-based leakage of personally identifiable information (PII) compared to ARMs.
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id arxiv_https___arxiv_org_abs_2603_02333
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Characterizing Memorization in Diffusion Language Models: Generalized Extraction and Sampling Effects
Luo, Xiaoyu
Yu, Wenrui
Li, Qiongxiu
Bjerva, Johannes
Computation and Language
Autoregressive language models (ARMs) have been shown to memorize and occasionally reproduce training data verbatim, raising concerns about privacy and copyright liability. Diffusion language models (DLMs) have recently emerged as a competitive alternative, yet their memorization behavior remains largely unexplored due to fundamental differences in generation dynamics. To address this gap, we present a systematic theoretical and empirical characterization of memorization in DLMs. We propose a generalized probabilistic extraction framework that unifies prefix-conditioned decoding and diffusion-based generation under arbitrary masking patterns and stochastic sampling trajectories. Theorem 4.3 establishes a monotonic relationship between sampling resolution and memorization: increasing resolution strictly increases the probability of exact training data extraction, implying that autoregressive decoding corresponds to a limiting case of diffusion-based generation by setting the sampling resolution maximal. Extensive experiments across model scales and sampling strategies validate our theoretical predictions. Under aligned prefix-conditioned evaluations, we further demonstrate that DLMs exhibit substantially lower memorization-based leakage of personally identifiable information (PII) compared to ARMs.
title Characterizing Memorization in Diffusion Language Models: Generalized Extraction and Sampling Effects
topic Computation and Language
url https://arxiv.org/abs/2603.02333