# Florian Naef: Relative intersection product, Whitehead-torsion and string topology

**Time: **
Tue 2022-11-01 10.15

**Location: **
Albano, house 1, Cramer room

**Participating: **
Florian Naef

**Abstract:**

Given a closed oriented manifold one can define an intersection product on the homology. This can be extended to local coefficient, and further made relative to the diagonal. I will explain how such a relative self-intersection product is not homotopy invariant (in contrast to the ordinary intersection product) and how this is picked up by string topology. Eventually, we will identify the error term with the trace of Whitehead torsion. More precisely, we will extract an invariant from a Poincare embedding of the diagonal (in the sense of J. Klein) that is the trace of (a version of) Reidemeister torsion. This is based on joint work with P. Safronov.