The conformal Yamabe constant of product manifolds

Abstract

Let (V,g) and (W,h) be compact Riemannian manifolds of dimension at least 3. We derive a lower bound for the conformal Yamabe constant of the product manifold (V x W, g+h) in terms of the conformal Yamabe constants of (V,g) and (W,h).Comment: 12 pages, to appear in Proc. AMS; v3: small changes, very last preprint version, close to published versio