The purpose of this collection is to make accessible in one place a number of the seminal research papers in the field of aritificial intelliigence. These papers cover a wide variety of topics; some are theoretical and some experimental. As many of the papers included here are difficult to find elsewhere, having originally been published in conference proceedings or journals that are no longer in print, the researcher or student will find this volume a valuable sourcebookof fundamental AI research. The editors have added useful introductions to each section and a comprehensive subject index.