  The development of nonmonotonic logic also owes a great deal to the applied side of AI. In fact, the need for a nonmonotonic analysis of a number of AI applications was as persuasive as the strategic considerations urged by McCarthy, and in many ways more influential on the shape of the formalisms that emerged. Here, we mention three such applications that appear to have been important for some of the early nonmonotonic logicians: belief revision, closed-world reasoning, and planning.