Abstract
Uniform discrete diffusion models (UDMs) commonly use explicit time conditioning, but we find that it can often be unnecessary in practice. In this paper, we first show that the population-optimal UDM predictor generally depends on time: time controls how much the model should trust the observed context. We then show that this dependence can become negligible in finite-data settings relevant to language. When a corrupted training sequence remains much closer to its original clean sequence than to competing training sequences, the empirical-optimal predictor is nearly insensitive to time over most of the diffusion trajectory, where the guarantee weakens toward the high-noise endpoint. Empirically, trained language UDMs exhibit limited time sensitivity over most of the trajectory, while time-agnostic predictors remain competitive with, and often outperform, time-conditioned models across datasets and training objectives. These results challenge the use of explicit time conditioning in UDMs: although the population optimum depends on time, explicitly conditioning on it may often be unnecessary in practice.
Keywords
Publication details
- Journal
- Not available
- Open access
- Green open access
Cite this article
APA 7
Hong, C., Lai, C. H., Hayakawa, S., Takida, Y., Ye, J. C., & Mitsufuji, Y. (2026). Does Uniform Discrete Diffusion Need Time? https://omanscience.com/en/articles/does-uniform-discrete-diffusion-need-time
MLA 9
Hong, Chunsan, et al. "Does Uniform Discrete Diffusion Need Time?" https://omanscience.com/en/articles/does-uniform-discrete-diffusion-need-time.
Chicago (author–date)
Hong, Chunsan, Chieh-Hsin Lai, Satoshi Hayakawa, Yuhta Takida, Jong Chul Ye, and Yuki Mitsufuji. 2026. "Does Uniform Discrete Diffusion Need Time?" https://omanscience.com/en/articles/does-uniform-discrete-diffusion-need-time.
Harvard
Hong, C., Lai, C. H., Hayakawa, S., Takida, Y., Ye, J. C. and Mitsufuji, Y. (2026) 'Does Uniform Discrete Diffusion Need Time?', Available at: https://omanscience.com/en/articles/does-uniform-discrete-diffusion-need-time.
Vancouver
Hong C, Lai CH, Hayakawa S, Takida Y, Ye JC, Mitsufuji Y. Does Uniform Discrete Diffusion Need Time? https://omanscience.com/en/articles/does-uniform-discrete-diffusion-need-time
IEEE
C. Hong, C. H. Lai, S. Hayakawa, Y. Takida, J. C. Ye, and Y. Mitsufuji, "Does Uniform Discrete Diffusion Need Time?," https://omanscience.com/en/articles/does-uniform-discrete-diffusion-need-time.