# The Groove of Math

## Filling the Details #5: Two words about the Atiyah-Hirzebruch Spectral Sequence

It’s finally time we shed some light on the technicalities behind this powerful tool. It took me some time digesting all these materials and I have to thank all the people who helped me understanding these passages. We will identify the differentials of the AHSS for spin-bordism (since it’s the one I need for my thesis), but the method we are going to use can be generalised to any AHSS, provided we have enough informations about the cohomology group of the spectra involved.

Proposition: Every $2$-homology class of a smooth 4-manifold is generated by a surface