Philipp Reiser (Univ Fribourg) - "Twisted suspensions, torus actions, and positive Ricci curvature"

The twisted suspension of a manifold can be seen as a smooth analogue of the classical suspension operation for topological spaces. Its construction is motivated by the spinning operation in knot theory and it is obtained by surgery on a fibre of a principal circle bundle over the given manifold. In this talk I will show that Riemannian metrics of positive Ricci curvature can be lifted along twisted suspensions. As application we obtain first examples of simply-connected manifolds of positive Ricci curvature with maximal symmetry rank in any dimension, and we obtain new examples of (rational) homology spheres with a Riemannian metric of positive Ricci curvature.
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