An overview of automated reasoning

Two general approaches to reasoning with imperfect information are discussed: nonmonotonic reasoning and a calculus of uncertainty. Default reasoning is posed as an approach that is potentially capable of integrating many facets of these two approaches. Practical requirements for default reasoning are then established. This is done by identifying a number of cases that involve incomplete and uncertain information and showing how they can be addressed by default reasoning. Parametric and symbolic reasoning are differentiated, and it is shown that both types are necessary. This distinction is important, as most approaches tend to neglect either the parametric or the symbolic aspect of default reasoning, thereby restricting its use to one of the two approaches discussed above. Five capabilities that are necessary to effect default reasoning are identified. The major characteristics for systems that handle incomplete and uncertain information as well as other types of imperfect information are established.>