Starting with the Euler characteristic in graph theory/combinatorics, we trace a brief history, first viewing it as an Euler class in topology, then as an obstruction to splitting of vector bundles and finally get to the more recent notion of the Euler class in algebra/geometry and its use as an obstruction to the splitting of projective modules. This recent notion has two approaches, Euler class groups and Chow-Witt groups, the second of which uses the Gersten-Witt complex as mentioned in the title. Time permitting, we hope to state results about both approaches.

- All seminars.
- Seminars for 2013