Low-dimensional manifolds with non-negative curvature and maximal symmetry rank. [Preprint]

We classify closed, simply connected n-manifolds of non-negative sectional curvature admitting an isometric torus action of maximal symmetry rank in dimensions 2≤n≤6. In dimensions 3k, k=1,2 there is only one such manifold and it is diffeomorphic to the product of k copies of the 3-sphere.