[woodgears]

Perhaps the "mood detector" isn't the most intuitive example. But imagine it's some sort of computer peripheral that several applications make use of. The problem seems simple until multiple agents start to mess with it. So you start out with steve's simple model, and you too will progress to what he ended up with eventually.

on/off seems easy, but it's hard in complex systems. Like how complex can it be to turn windows vista on and off, right?