Fecha y lugar: Lunes, Nov 22, 16:30 hrs CST.

Por: Lee Kennard, Syracuse University.

Abstract: In joint work with Michael Wiemeler and Burkhard Wilking at the University of Muenster, we prove optimal estimates on the weighted girth (or systole) of graphs with small first Betti number. By applying results from the theory of regular matroids, this implies results for torus representations having the special property that all isotropy groups are connected. These result in turn imply strong obstructions to the existence of isometric torus actions on positively curved Riemannian manifolds.