design called flexible graph connectivity: given a multi-graph G=(V,E) with non-negative costs on the edges
and a partition of E into a set of safe edges and a set of unsafe edges, find a cheapest connected spanning
subgraph H=(V,F) of G that stays connected even after the failure of one unsafe edge (that is, H-e is
connected for each unsafe edge e in F). Recent research has focused on approximation algorithms for this
model and its extensions, and this has raised perplexing questions. The talk will cover the AHM model and its
extensions, as well as some approximation algorithms for these models.