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 variance exploding diffusion model


Leveraging Drift to Improve Sample Complexity of Variance Exploding Diffusion Models

Neural Information Processing Systems

Variance exploding (VE) based diffusion models, an important class of diffusion models, have shown state-of-the-art (SOTA) performance. However, only a few theoretical works analyze VE-based models, and those works suffer from a worse forward convergence rate 1/\text{poly}(T) than the \exp{(-T)} of variance preserving (VP) based models, where T is the forward diffusion time and the rate measures the distance between forward marginal distribution q_T and pure Gaussian noise. The slow rate is due to the Brownian Motion without a drift term. In this work, we design a new drifted VESDE forward process, which allows a faster \exp{(-T)} forward convergence rate. With this process, we achieve the first efficient polynomial sample complexity for a series of VE-based models with reverse SDE under the manifold hypothesis.