One-Step Generative Modeling via Wasserstein Gradient Flows
Abstract
Diffusion models and flow-based methods have achieved strong results in image generation, but often rely on costly iterative sampling. We introduce W-Flow, a framework that compresses a Wasserstein gradient flow into a one-step neural generator. By minimizing the Sinkhorn divergence, W-Flow transports a reference distribution toward the data distribution through efficient optimal-transport updates that capture global distributional discrepancies. We prove that, under suitable assumptions, the finite-sample training dynamics converge to the continuous-time distributional dynamics. Empirically, W-Flow sets a new state of the art in one-step ImageNet generation, with improved mode coverage and domain transfer. We will also discuss extensions using alternative energy functionals and applications to post-training.
The vanishing limit of a rigid body in 3D viscous incompressible fluid
Abstract
We consider the evolution of a small rigid body in an incompressible viscous fluid filling the whole space R^3 . When the small rigid body shrinks to a point in the sense that its density is constant, we prove that the solution of the fluid-rigid body system converges to a solution of the Navier–Stokes equations in the full space. Based on some L^p − L^q estimates of the fluid–structure semigroup and a fixed point argument, we obtain a uniform estimate of velocity of the rigid body. This allows us to construct admissible test functions which plays a key role in the procedure of passing to the limit. This is a joint work with Pei Su (Nantes).
Regularity of oblique transmission problems
Abstract
I will present new regularity results in the case of flat interfaces, where the transmission condition may depend on both the normal and tangential derivatives of the solution. This condition can be viewed as a nonlinear coupling of oblique derivatives across the interface. Our main result establishes optimal piecewise $C^{1,\alpha}$ regularity for viscosity solutions.