Prof. Dr. Andrzej Szczepański (University of Gdansk): "Intersection forms of 4-dimensional oriented almost-flat manifolds"
Nov 22, 2017 from 10:15 AM to 11:45 AM
LMS 4 - Raum 312 - Diskussionsraum
Abstract:
I will present an introduction to flat and almost flat manifolds. Then I will define a spin-structure on such objects and finally I will prove the following:
Let M be any almost-flat oriented 4-manifold different from the torus with intersection form Q_{M}. Then Q_{M} = 0 if the first Betti number b_1(M) = 1, Q_{M} = H if b_1(M) = 2 and Q_{M} = 2H if b_1(M) = 3. Here H is the hyperbolic form with intersection matrix [0,1 1,0] of rank 2.
Einladender: R. Weidmann