I received last week two interesting pieces of literature which, on the face of it, should have nothing in common: Terry Pratchet’s ‘Making Money‘ (the latest installment in his ‘Discworld’ novels) and the preliminary schedule of the Society for American Archaeology’s conference in Vancouver. The connection between the two turns on an ingenious device, central for the plot of ‘Making Money’: The Glooper.
‘Mr. Hubert believes that this… device is a sort of crystal ball for showing the future,’ said Bent, and rolled his eyes.
‘Possible futures. Would Mr. Lipstick like to see it in operation?’ said Hubert, vibrating with enthusiasm and eagerness.[…]
‘The Glooper, as it is affectionately known, is what I call a quote analogy machine unquote. It solves problems not by considering them as a numerical exercise but by actually duplicating them in a form we can manipulate: in this case, the flow of money and its effects within our society become water flowing through a glass matrix – the Glooper. The geometrical shape of certain vessels, the operation of valves and, although i say so myself, ingenious tipping buckets and flow-rate propellers enable the Glooper to simulate quite complex transactions. We can change the starting conditions, too, to learn the rules inherent in the system. For example, we can find out what happens if you halve the labour force in the city by the adjustment of a few valves, rather than by going out into the streets and killing people.’
‘A big improvement! Bravo!’ said Moist desperately, and started to clap. No one joined in.
Strangely enough, this passage is one of the best descriptions you’ll find of what agent-based models actually do (minus the water, glass beakers, tipping buckets etc), and what you can do with them. I haven’t done much with my agent modeling work of late, so reading about the Glooper almost got me charged up enough to download the latest version of Netlogo and to update/refine some models I’ve got kicking around. Which is timely, since I read almost immediately thereafter that at the SAA conference, there is a session called ‘Parallel Worlds: Interdisciplinary Agent-Based Models of Socioecological Processes and Complexity’ (scheduled for Friday March 28). Tim Kohler, Mark Lake, Luke Premo and many other excellent archaeologists-cum-agent-modelers are going to participate, so it looks like it should be a fantastic event.
I was at the CAA in Fargo a few years ago, in a session on agent-modeling, and it was interesting to observe how the agent modelers divided into two broad camps: those who tried to develop models that accounted for everything, and those who tried to develop limited models that tried to capture one specific aspect. I count myself amongst the latter: if I aim small, my results are, paradoxically, applicable to wider situations because I haven’t tried to account for everything (and thus be relevant only to what I’ve mapped). The Glooper, as it transpires in the novel, becomes such an excellent model that it maps one-to-one: changing the model changes reality.
If you’re interested in developing agent models, the learning curve can be steep. My recommendation is to download Netlogo, join the user group on Yahoo groups, do some of the tutorials (included in the documentation), and start mucking about. Other resources are here.