A closer look at the non-Hopfianness of $BS(2,3)$

The Baumslag-Solitar group $BS(2,3)$, is a so-called non-Hopfian group, meaning that it has an epimorphism $\phi$ onto itself, not injective. In particular this equivalent to saying $BS(2,3)$ non-trivial quotient isomorphic itself. As consequence the Cayley graph of itself up change generators. We describe on graph-level and take closer look at most common $\phi$. show its kernel free infinite rank with explicit set Finally we how appears as morphism fundamental groups induced by some continuous map. This point view was communicated author Gilbert Levitt.