  Connectivity and layout of underlying networks largely determine the behavior
of many environments. For example, transportation networks determine the flow
of traffic in cities, or maps determine the difficulty and flow in games.
Designing such networks from scratch is challenging as even local network
changes can have large global effects. We investigate how to computationally
create networks starting from {\em only} high-level functional specifications.
Such specifications can be in the form of network density, travel time versus
network length, traffic type, destination locations, etc. We propose an integer
programming-based approach that guarantees that the resultant networks are
valid by fulfilling all specified hard constraints, and score favorably in
terms of the objective function. We evaluate our algorithm in three different
design settings (i.e., street layout, floorplanning, and game level design) and
demonstrate, for the first time, that diverse networks can emerge purely from
high-level functional specifications.
