Semantical considerations on nonmonotonic logic
Artificial Intelligence
Formalizing nonmonotonic reasoning systems
Artificial Intelligence
Structural complexity 1
Hard problems for simple default logics
Artificial Intelligence - Special issue on knowledge representation
Conditional entailment: bridging two approaches to default reasoning
Artificial Intelligence
Generalizations of Opt P to the polynomial hierarchy
Theoretical Computer Science
Constructive default logic and the control of defeasible reasoning
ECAI '92 Proceedings of the 10th European conference on Artificial intelligence
Some direct theories of nonmonotonic inheritance
Handbook of logic in artificial intelligence and logic programming (vol. 3)
Default reasoning using classical logic
Artificial Intelligence
Lexicographic priorities in default logic
Artificial Intelligence
Nonmonotonic Logic: Context-Dependent Reasoning
Nonmonotonic Logic: Context-Dependent Reasoning
Prioritized Autoepistemic Logic
JELIA '94 Proceedings of the European Workshop on Logics in Artificial Intelligence
Adding Priorities and Specificity to Default Logic
JELIA '94 Proceedings of the European Workshop on Logics in Artificial Intelligence
Compiling reasoning with and about preferences into default logic
IJCAI'97 Proceedings of the 15th international joint conference on Artifical intelligence - Volume 1
Complexity of argument-based default reasoning with specificity
AI Communications
A framework for compiling preferences in logic programs
Theory and Practice of Logic Programming
Problem solving with insufficient resources
International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems
Complexity of argument-based default reasoning with specificity
AI Communications
On the semantics of logic programs with preferences
Journal of Artificial Intelligence Research
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In default reasoning, usually not all possible ways of resolving conflicts between default rules are acceptable. Criteria expressing acceptable ways of resolving the conflicts may be hardwired in the inference mechanism, for example specificity in inheritance reasoning can be handled this way, or they may be given abstractly as an ordering on the default rules. In this article we investigate formalizations of the latter approach in Reiter's default logic. Our goal is to analyze and compare the computational properties of three such formalizations in terms of their computational complexity: the prioritized default logics of Baader and Hollunder, and Brewka, and a prioritized default logic that is based on lexicographic comparison. The analysis locates the propositional variants of these logics on the second and third levels of the polynomial hierarchy, and identifies the boundary between tractable and intractable inference for restricted classes of prioritized default theories.