  Many real systems can be described by a set of interacting entities forming a
complex network. To some surprise, these have been shown to share a number of
structural properties regardless of their type or origin. It is thus of vital
importance to design simple and intuitive models that can explain their
intrinsic structure and dynamics. These can, for instance, be used to study
networks analytically or to construct networks not observed in real life. Most
models proposed in the literature are of two types. A model can be either
static, where edges are added between a fixed set of nodes according to some
predefined rule, or evolving, where the number of nodes or edges increases over
time. However, some real networks do not grow but rather shrink, meaning that
the number of nodes or edges decreases over time. We here propose a simple
model of shrinking networks called the war pact model. We show that networks
generated in such a way exhibit common structural properties of real networks.
Furthermore, compared to classical models, these resemble international trade,
correlates of war, Bitcoin transactions and other networks more closely.
Network shrinking may therefore represent a reasonable explanation of the
evolution of some networks and greater emphasis should be put on such models in
the future.
