A metrization theorem for edge-end spaces of infinite graphs

Abstract

We prove that the edge-end space of an infinite graph is metrizable if and only if it is first-countable. This strengthens a recent result by Aurichi, Magalhaes Jr.\ and Real (2024). Our central graph-theoretic tool is the use of tree-cut decompositions, introduced by Wollan (2015) as a variation of tree decompositions that is based on edge cuts instead of vertex separations. In particular, we give a new, elementary proof for Kurkofka's result (2022) that every infinite graph has a tree-cut decomposition of finite adhesion into its $\omega$-edge blocks. Along the way, we also give a new, short proof for a classic result by Halin (1984) on $K_{k,\kappa}$-subdivisions in $k$-connected graphs, making this paper self-contained.