Relatively Hyperbolic Groups with Semistable Peripheral Subgroups (2101.05923v2)

Abstract: Suppose $G$ is a finitely presented group that is hyperbolic relative to ${\bf P}$ a finite collection of 1-ended finitely generated proper subgroups of $G$. If $G$ and the ${\bf P}$ are 1-ended and the boundary $\partial (G,{\bf P})$ has no cut point, then $G$ was known to have semistable fundamental group at $\infty$. We consider the more general situation when $\partial (G,{\bf P})$ contains cut points. Our main theorem states that if $G$ is finitely presented and each $P\in {\bf P}$ is finitely generated and has semistable fundamental group at $\infty$, then $G$ has semistable fundamental group at $\infty$.