Original article at: http://www.math.washington.edu/~ejpecp/ECP/viewarticle.php?id=1569

Martingale Representation and a Simple Proof of Logarithmic Sobolev Inequalities on Path Spaces

Mireille Capitaine, Universite Paul-Sabatier
Elton P. Hsu, Northwestern University
Michel Ledoux, Universite Paul-Sabatier

Abstract

We show how the Clark-Ocone-Haussmann formula for Brownian motion on a compact Riemannian manifold put forward by S. Fang in his proof of the spectral gap inequality for the Ornstein-Uhlenbeck operator on the path space can yield in a very simple way the logarithmic Sobolev inequality on the same space. By an appropriate integration by parts formula the proof also yields in the same way a logarithmic Sobolev inequality for the path space equipped with a general diffusion measure as long as the torsion of the corresponding Riemannian connection satisfies Driver's total antisymmetry condition.

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Original article at: http://www.math.washington.edu/~ejpecp/ECP/viewarticle.php?id=1569