Poster
Efficient Sampling of Stochastic Differential Equations with Positive Semi-Definite Models
Anant Raj · Umut Simsekli · Alessandro Rudi
Great Hall & Hall B1+B2 (level 1) #1006
Abstract:
This paper deals with the problem of efficient sampling from a stochastic differential equation, given the drift function and the diffusion matrix. The proposed approach leverages a recent model for probabilities (Rudi and Ciliberto, 2021) (the positive semi-definite -- PSD model) from which it is possible to obtain independent and identically distributed (i.i.d.) samples at precision with a cost that is where is the dimension of the model, the dimension of the space. The proposed approach consists in: first, computing the PSD model that satisfies the Fokker-Planck equation (or its fractional variant) associated with the SDE, up to error , and then sampling from the resulting PSD model. Assuming some regularity of the Fokker-Planck solution (i.e. -times differentiability plus some geometric condition on its zeros) We obtain an algorithm that: (a) in the preparatory phase obtains a PSD model with L2 distance from the solution of the equation, with a model of dimension where is the fractional power to the Laplacian, and total computational complexity of and then (b) for Fokker-Planck equation, it is able to produce i.i.d.\ samples with error in Wasserstein-1 distance, with a cost that is per sample. This means that, if the probability associated with the SDE is somewhat regular, i.e. , then the algorithm requires in the preparatory phase, and for each sample. Our results suggest that as the true solution gets smoother, we can circumvent the curse of dimensionality without requiring any sort of convexity.
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