Applications of circumscription to formalizing common-sense knowledge
Artificial Intelligence
A first-order conditional logic for prototypical properties
Artificial Intelligence
A logical framework for default reasoning
Artificial Intelligence
An approach to default reasoning based on a first-order conditional logic: revised report
Artificial Intelligence
Nonmonotonic reasoning, preferential models and cumulative logics
Artificial Intelligence
Model-preference default theories
Artificial Intelligence
Hard problems for simple default logics
Proceedings of the first international conference on Principles of knowledge representation and reasoning
System Z: a natural ordering of defaults with tractable applications to nonmonotonic reasoning
TARK '90 Proceedings of the 3rd conference on Theoretical aspects of reasoning about knowledge
Semantical considerations on nonmonotonic logic
IJCAI'83 Proceedings of the Eighth international joint conference on Artificial intelligence - Volume 1
A theorem prover for prioritized circumscription
IJCAI'89 Proceedings of the 11th international joint conference on Artificial intelligence - Volume 1
A semantical approach to stable inheritance reasoning
IJCAI'89 Proceedings of the 11th international joint conference on Artificial intelligence - Volume 2
A clash of intuitions: the current state of nonmonotonic multiple inheritance systems
IJCAI'87 Proceedings of the 10th international joint conference on Artificial intelligence - Volume 1
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An approach for introducing default reasoning into first-order Horn clause theories is described. A default theory is expressed as a set of strict implications of the form α1 Λ ... Λ αn ⊃ β, and a set of default rules of the form α1 Λ ... Λ αn ⇒ β, where the αi and β are function-free literals. A partial order of sets of formulae is obtained from these sets of (strict and default) implications. Default reasoning is defined with respect to this ordering and a set of contingent ground facts. Crucially, only strict implications appear in this structure. Consequently the complexity of default reasoning is that of classical reasoning, together with an attendant overhead for manipulating the structure. This overhead is O(n2), where n is the number of original formulae. Hence for defaults in propositional Horn clause form time complexity is O(n2m) where m is the total length of the original formulae. The approach is sound, in that default reasoning in this structure is proven to conform to that of an extant system for default reasoning.