The Fourth International Workshop on Nonmonotonic Reasoning brought together active researchers in nonmonotonic reasoning to discuss current research, results, and problems of both theoretical and practical natures. There was lively discussion on a number of issues, including future research directions for the field.
'I can't believe that!' said Alice'Can't you?' the Queen said in a pitying tone. 'Try again: draw a long breadth, and shut your eyes.' Alice laughed. 'There's no use trying,' she said: 'one can't believe impossible things.' 'I daresay you haven't had much practice,' said the Queen. 'When I was your age, I always did it for half-an-hour a day. Why, sometimes I've believed as many as six impossible things before breakfast.'
Truth maintenance is a collection of techniques for doing belief revision. A truth maintenance system's task is to maintain a set of beliefs in such a way that they are not known to be contradictory and no belief is kept without a reason. Truth maintenance systems were introduced in the late seventies by Jon Doyle and in the last five years there has been an explosion of interest in this kind of systems. In this paper we present an annotated bibliography to the literature of truth maintenance systems, grouping the works referenced according to several classifications.