Daily Archives: 14 October, 2009

A Subway Metaphor

Many years ago I read a science fiction story which has always stayed with me – although I’m buggered if I can remember the title or the author.

It was set in the not too distant future. Another new line was about to be opened on the New York City Subway [In the comments Rozallin points out that it was, in fact, probably Boston and not NYC]. Mathematicians were warning that the line shouldn’t be opened as every new line increased the complexity of the network and they had calculated that opening this particular line would push the network over some limit and would make it theoretically unsolvable. They worried that the safety of passengers couldn’t be guaranteed if they were travelling on an unsolvable graph.

Of course, the mathematicians were ignored. And, of course, trains started going missing soon after the line was opened. And that’s where our hero (a kind of topological Indiana Jones, if I recall correctly) came in.

For some reason, that’s the image that sometimes pops into my head when I’m working on large application that has had random pieces of code added to it by various people over long periods of time. I worry that the system will eventually become so complex that any train (or, more likely, CPU) that is set running on it will vanish into the depths of complexity, never to be seen again.

I had that feeling particularly strongly this afternoon. This system really needs to be brought under control.