Tuesday, May 22, 2007


This is a guest post written by Jacob Haqq-Misra. His blog "Reflections, Ideas, and Schemes" can be found here.


Several of Chris' entries deal with road trips and navigation. In keeping with this theme while maintaining my own flavor, I'll begin with a simple question: what is a road? Of course, I mean this question in a very general sense. The Oxford English Dictionary has a number of definitions for the word; I'll just use one of them:

"An ordinary line of communication used by persons passing between different places, usually one wide enough to admit of the passage of vehicles as well as of horses or travelers on foot."

The second part of the definition assumes the use of land vehicles, but the first part is more general. A road is a special case of an edge on a graph (and indeed this is the basis for how navigational software works). But a graph (technically a directed graph) is a general structure, not limited to land travel or even the transport of people. The Internet, airline routes, and satellite networks are all examples of high-traffic directed graphs.

Typically, people assume a road to be a path along which a motor vehicle can travel, but if we take the more general notion of a directed graph edge to create a line of communication, then new roads are everywhere! Interstate construction is only a small fraction of the new "roads" built in the modern-era, since technological advancements (including the building of interstates) have contributed to the flattening of the world.

Asphalt and concrete are fading away; the roads of today are built with fiber-optics and satellites.

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