  We investigate the computational complexity of separating two distinct
vertices s and z by vertex deletion in a temporal graph. In a temporal graph,
the vertex set is fixed but the edges have (discrete) time labels. Since the
corresponding Temporal (s, z)-Separation problem is NP-hard, it is natural to
investigate whether relevant special cases exist that are computationally
tractable. To this end, we study restrictions of the underlying (static)
graph---there we observe polynomial-time solvability in the case of bounded
treewidth---as well as restrictions concerning the "temporal evolution" along
the time steps. Systematically studying partially novel concepts in this
direction, we identify sharp borders between tractable and intractable cases.
