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An introduction to invariants of links and 3-manifolds obtained by counting graph configurations
Student-Run Geometry/Topology Seminar| Speaker: | Christine Lescop, Institut Fourier |
| Location: | 2112 MSB |
| Start time: | Tue, Oct 15 2013, 2:30PM |
We will explain how to count graph configurations in 3-manifolds in order to obtain invariants of knots, links and 3-manifolds, following Gauss (1833), and, more recently, Witten, Bar-Natan, Kontsevich and others. We will warm up with several equivalent definitions of the simplest of these invariants that is the Gauss linking number of two-component links, and pursue with a definition of the Casson-Walker invariant of rational homology spheres as an algebraic count of configurations of the theta-graph.