2 problems

Let $G$ be the fundamental group of a non-positively curved graph manifold, let $X$ be its universal cover, and let $T_{\infty}$ be the Bass–Serre tree of the graph-of-groups decom…

Let $G$ act geometrically on two $\operatorname{CAT}(0)$ spaces $Y$ and $Y'$ whose $d_L$-metrics stabilize. Let $\partial_M^{\kappa}Y$ and $\partial_M^{\kappa}Y'$ denote their…