  Core-periphery networks are structures that present a set of central and
densely connected nodes, namely the core, and a set of non-central and sparsely
connected nodes, namely the periphery. The rich-club refers to a set in which
the highest degree nodes show a high density of connections. Thus, a network
that displays a rich-club can be interpreted as a core-periphery network in
which the core is made up by a number of hubs. In this paper, we test the
resilience of networks showing a progressively denser rich-club and we observe
how this structure is able to affect the network measures in terms of both
cohesion and efficiency in information flow. Additionally, we consider the case
in which, instead of making the core denser, we add links to the periphery.
These two procedures of core and periphery thickening delineate a decision
process in the placement of new links and allow us to conduct a scenario
analysis that can be helpful in the comprehension and supervision of complex
networks under the resilience perspective. The advantages of the two
procedures, as well as their implications, are discussed in relation to both
network effciency and node heterogeneity.
