Scale-free Networks in the Presence of Constraints: An Empirical Investigation of the Airline Route Network

Abstract

Classifying the types of networks has been a focus of analysis in the

recent, small-world research. A unifying theory has been introduced to

provide an integrative perspective on the statistical properties of a

variety of real-world networks. This theory postulates that the existence

of constraints deters the emergence of a scale-free network. For

example, the theory argues that the constraints of airport capacity limit

the growth of air traffic, blocking the emergence of a scale-free network.

We challenge this argument by reexamining the context of the airline

industry. We empirically show that the U. S. airline route network is a

scale-free network despite the presence of capacity constraints. We

propose a new avenue for future research.