In this talk, I will give an overview of known results on the stable cohomology of the automorphism groups of free groups with twisted coefficients. After explaining the notion of wheeled PROPs, I will describe a wheeled PROP structure on the stable cohomology of automorphism groups of free groups with some particular coefficients. I will explain how cohomology classes, constructed previously by Kawazumi, can be interpreted using this wheeled PROP structure and I will construct a morphism of wheeled PROPs from a PROP given in terms of functor homology and the wheeled PROP evoked previously. This is joint work with Nariya Kawazumi.[-]

A spin structure on a closed surface $S$ of genus $g \geq 2$ is a covering of the unit tangent bundle of $S$ witch restricts to a standard covering of the fiber. Such a spin structure has a parity, even or add. The spin mapping class is the stabilizer of such a spin structure in the mapping class group of $S$. We use a subgraph of the curve graph to construct an explicit generating set of the spin mapping class group consisting of Dehn twists about a system of $2g-1$ simple closed curves.[-]