Nonmonotonic reasoning, preferential models and cumulative logics
Artificial Intelligence
Probabilistic semantics for nonmonotonic reasoning: a survey
Proceedings of the first international conference on Principles of knowledge representation and reasoning
On the consistency of defeasible databases
Artificial Intelligence
What does a conditional knowledge base entail?
Artificial Intelligence
Conditional entailment: bridging two approaches to default reasoning
Artificial Intelligence
Recognition of q-Horn formulae in linear time
Discrete Applied Mathematics
Qualitative probabilities for default reasoning, belief revision, and causal modeling
Artificial Intelligence
From statistical knowledge bases to degrees of belief
Artificial Intelligence
Nonmonotonic reasoning, conditional objects and possibility theory
Artificial Intelligence
Default reasoning from conditional knowledge bases: complexity and tractable cases
Artificial Intelligence
Default Reasoning: Causal and Conditional Theories
Default Reasoning: Causal and Conditional Theories
Nonmonotonic reasoning: from complexity to algorithms
Annals of Mathematics and Artificial Intelligence
A Maximum Entropy Approach to Nonmonotonic Reasoning
IEEE Transactions on Pattern Analysis and Machine Intelligence
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
Inconsistency management and prioritized syntax-based entailment
IJCAI'93 Proceedings of the 13th international joint conference on Artifical intelligence - Volume 1
Maximum entropy and variable strength defaults
IJCAI'99 Proceedings of the 16th international joint conference on Artifical intelligence - Volume 1
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We present new tractable cases for default reasoning from conditional knowledge bases. In detail, we introduce q-Horn conditional knowledge bases, which allow for a limited use of disjunction. We show that previous tractability results for Ɛ-entailment, proper Ɛentailment, and z- and z+-entailment in the Horn case can be extended to the q-Horn case. Moreover, we present feedback-free-Horn conditional knowledge bases, which constitute a new, meaningful class of conditional knowledge bases. We show that the maximum entropy approach and lexicographic entailment are tractable in the feedback-free-Horn case. Our results complement and extend previous results, and contribute in refining the tractability/ intractability frontier of default reasoning from conditional knowledge bases.