-algebras, positive scalar curvature, and the Novikov conjecture
We generalize the concept of warped manifold to Riemannian submersions π: M → B between two compact Riemannian manifolds and in the following way. If f: B → (0,∞) is a smooth function on B which is extended to a function f̂ = f ∘ π constant along the fibres of π then we define a new metric on M by , where and denote the bundles of horizontal and vertical vectors. The manifold obtained that way is called a warped submersion. The function f is called a warping function. We show a necessary...