On hyperbolicity and virtual freeness of automorphism groups

We show that word hyperbolicity of automorphism groups of graph products $G_\Gamma$ and of Coxeter groups $W_\Gamma$ depends strongly on the shape of the defining graph $\Gamma$. We also characterized those $Aut(G_\Gamma)$ and $Aut(W_\Gamma)$ in terms of $\Gamma$ that are virtually free.