This is an announcement for the paper "Isoperimetric and concentration inequalities - Part I: Equivalence under curvature lower bound" by Emanuel Milman.
Abstract: It is well known that isoperimetric inequalities imply in a very general measure-metric-space setting appropriate concentration inequalities. The former bound the boundary measure of sets as a function of their measure, whereas the latter bound the measure of sets separated from sets having half the total measure, as a function of their mutual distance. We show that under a lower bound condition on the Bakry--'Emery curvature tensor of a Riemannian manifold equipped with a density, completely general concentration inequalities imply back their isoperimetric counterparts, up to dimension \emph{independent} bounds. As a corollary, we can recover and extend all previously known (dimension dependent) results by generalizing an isoperimetric inequality of Bobkov, and provide a new proof that under natural convexity assumptions, arbitrarily weak concentration implies a dimension independent linear isoperimetric inequality. Further applications will be described in a subsequent work. Contrary to previous attempts in this direction, our method is entirely geometric, continuing the approach set forth by Gromov and adapted to the manifold-with-density setting by Morgan.
Archive classification: math.DG math.FA
Remarks: 30 pages; second part involving numerous applications will appear
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0902.1560
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http://arXiv.org/abs/0902.1560
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