Quadratic functions, Spin structures and low-dimensional topology
Abstract: Ever since the beginning of algebraic topology, quadratic forms have played a prominent rôle. For instance, on surfaces, there is a very nice interpretation of quadratic forms as spin structures.
There is a new analog in dimension three: complex spin structures embed into the space of quadratic functions over the linking pairing. Consequences and connections with invariants of 3-manifolds will be also be discussed.