Nonmonotonic Reasoning: Is the Answer Harder Than the Question?

Incompleter information is pervasive in most real-world reasoning situations. In order to act in, or to interact with, the real world, agents must have the ability to make reasonable assumptions about areas where their knowledge is not definitive. The field of Nonmonotonic Reasoning aspires to giving a principled account of how reasoning and action can occur in the absence of complete information.