abstract = "Routing plays a fundamental role in network
applications, but it is especially challenging in Delay
Tolerant Networks (DTNs). These are a kind of mobile ad
hoc networks made of, e.g., (possibly, unmanned)
vehicles and humans where, despite a lack of continuous
connectivity, data must be transmitted while the
network conditions change due to the nodes mobility. In
these contexts, routing is NP-hard and is usually
solved by heuristic store and forward replication-based
approaches, where multiple copies of the same message
are moved and stored across nodes in the hope that at
least one will reach its destination. Still, the
existing routing protocols produce relatively low
delivery probabilities. Here, we genetically improve
two routing protocols widely adopted in DTNs, namely,
Epidemic and PRoPHET, in the attempt to optimize their
delivery probability. First, we dissect them into their
fundamental components, i.e., functionalities such as
checking if a node can transfer data, or sending
messages to all connections. Then, we apply Genetic
Improvement (GI) to manipulate these components as
terminal nodes of evolving trees. We apply this
methodology, in silico, to six test cases of urban
networks made of hundreds of nodes and find that GI
produces consistent gains in delivery probability in
four cases. We then verify if this improvement entails
a worsening of other relevant network metrics, such as
latency and buffer time. Finally, we compare the logics
of the best evolved protocols with those of the
baseline protocols, and we discuss the generalisability
of the results across test cases.",