The term "agent" is one of those catchwords that mean widely differing things to different people. To telecommunications people it is little more than a mobile piece of code that may be executed at any place. At the other extreme, AI people often associate with agents human-like traits such as social behavior. In between, software people view agents as fairly self-contained pieces of software that, at the low end, pretty much act like objects and, at the high end, more or less auto- mously decide when and how to react to stimuli or proactively initiate effects that can be observed from their...