Attunement to Constraints in Nonmonotonic Reasoning∗

Attunement to Constraints in Nonmonotonic Reasoning Attunement to Constraints in Nonmonotonic Reasoning

Reducing Query Answering to Satisfiability in Nonmonotonic Logics

We propose a unifying view of negation as failure, integrity constraints, and epistemic queries in nonmonotonic reasoning. Specifically, we study the relationship between satisfiability and logical implication in nonmonotonic logics, showing that, in many nonmonotonic formalisms, it is possible and easy to reduce logical implication to satisfiability. This result not only allows for establishin...

From Query Answering to Satissability in Nonmonotonic Logics

We propose a unifying view of negation as failure, integrity constraints, and epistemic queries in nonmonotonic reasoning. Specii-cally, we study the relationship between satis-ability and logical implication in nonmono-tonic logics, showing that, in many nonmono-tonic formalisms, it is possible and easy to reduce logical implication to satissability. This result not only allows for establishin...

Expressiveness vs. Complexity in Nonmonotonic Knowledge Bases: Propositional Case

We study the trade-off between the expressive abilities and the complexity of reasoning in propositional nonmonotonic knowledge bases. We first analyze, in an expressive epistemic modal framework, the most popular forms of nonmonotonic mechanisms used in knowledge representation: in particular, we prove that epistemic queries and epistemic integrity constraints are naturally expressed through t...

Logic in Nonmonotonic Reasoning

We present a conceptual description of nonmonotonic formalisms as essentially two-layered reasoning systems consisting of a monotonic logical system, coupled with a mechanism of a reasoned choice of default assumptions. On this ‘surgery’, the main features of a nonmonotonic formalism are determined by the interplay between its logical basis and the nonmonotonic overhead. Furthermore, it allows ...