### Time and place

Friday, July 16, 2021 virtually### Speakers and Format

We will have short virtual edition of the Bavarian Geometry & Topology Metting -- hopefully the last virtual one! We will have an afternoon of talks to stay in touch and catch up. To facilitate interaction in these remote times, we will have opportunities to chat to other participants in between and afterwards.### Connection info

The talks will be on zoom. During the break and after the last talk we will use gather.town. This is an online platform where you get a little avatar and can walk around a floor plan; when you get close to others you hear and can join their conversation. Hopefully this simulates somewhat of a Meeting experience.zoom link: Enter the lecture hall here! The password is the shape of the Bavarian donut above, mathematically speaking... (all lower case: *****)

gather.town link: Enter the beer garden! Same password as for the lectures.

### Schedule

13:00-14:00 | Markus Land (Univ. Copenhagen) | ## Stable cohomology of orthogonal/symplectic groups over ZI will explain how to calculate the stable mod 2 cohomology of orthogonal/symplectic groups over Z, focussing on similarities and differences to the calculation of the stable mod 2 cohomology of mapping class groups of oriented surfaces. This is joint with Hebestreit and Nikolaus and builds on earlier joint work with Calmès, Dotto, Harpaz, Hebestreit, Moi, Nardin, Nikolaus, and Steimle on Grothendieck—Witt theory of rings of integers in number fields. |

14:15-15:15 | Jonas Stelzig (LMU) | ## Very non-integrable almost complex structures: An h-principle and cohomological propertiesAn almost complex structure is everywhere (resp. maximally) non-integrable if its Nijenhuis tensor is everywhere nonzero (resp. of maximal rank). Such structures arise naturally in some familiar (but rather special) geometric situations, like nearly Kähler manifolds or Twistor spaces. We will discuss when they exist in general (spoiler: not always, but surprisingly often) and what cohomological properties they have. In particular, we investigate a recent generalization of Dolbeault cohomology to the non-integrable setting (spoiler: the latter is often infinite dimensional, even on compact manifolds). Joint work with R. Coelho and G. Placini. |

coffee break | join us on gather.town! | |

15:45-16:45 | Gregor Schaumann (Uni Würzburg) | ## What do TFTs measure?Topological field theories (TFT) are a functorial assignment of manifold invariants. However, given a generic TFT Z and a manifold M, the topological content of the assigned invariant Z(M) is unclear. The slogan of this talk is, that in many cases Z(M) can be thought of as measuring flat bundles of a given type on M. To make this precise in some cases, we first recall the cases of Dijkgraaf-Witten and Chern-Simons TFTs. Then we consider the 2-dimensional part of 3-dimensional TFTs with defects for finite tensor categories. One might hope to find similar structures for other TFTs defined by factorization algebras. This is based on joint work with Christoph Schweigert and Jürgen Fuchs. |

16:45 - ? | afterparty | extended Q & A, open discussion, and socializing on gather.town |

gather.town session funded by