AI Magazine is an official publication of the Association for the Advancement of Artificial Intelligence (AAAI). It is published four times each year in fall, winter, spring, and summer issues, and is sent to all members of the Association and subscribed to by most research libraries. Back issues are available on-line (issues less than 18 months old are only available to AAAI members). The purpose of AI Magazine is to disseminate timely and informative expository articles that represent the current state of the art in AI and to keep its readers posted on AAAI-related matters. The articles are selected for appeal to readers engaged in research and applications across the broad spectrum of AI.