 One of these emerged in computer science. Since the beginning of computing, programmers have developed procedures by which databases can be updated. The development of Artificial Intelligence inspired computer scientists to construct more sophisticated models of database updating. The truth maintenance systems developed by Jon Doyle (1979) were important in this development. One of the most significant theoretical contributions was a 1983 paper by Ronald Fagin, Jeffrey Ullman and Moshe Vardi, in which they introduced the notion of database priorities. 