the computational properties of qualitative spatial reasoning have been investigated to some degree. However, the question of the boundary between polynomial and NP-hard reasoning problems has not been addressed yet. ...
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the computational properties of qualitative spatial reasoning have been investigated to some degree. However, the question of the boundary between polynomial and NP-hard reasoning problems has not been addressed yet. In this paper we explore this boundary in the "Region Connection Calculus" RCC-8. We extend Bennett's encoding of RCC-8 in modal logic. Based on this encoding, we prove that reasoning is NP-complete in general and identify a maximal tractable subset of the relations in RCC-8 that contains all base relations. Further, we show that for this subset path-consistency is sufficient for deciding consistency. (C) 1999 Published by Elsevier B.V. All rights reserved.
Recently there has been increased interest in logicprogramming-based default reasoning approaches which are not using negation-as-failure in their object language. Instead, default reasoning is modelled by rules and ...
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ISBN:
(纸本)3540667490
Recently there has been increased interest in logicprogramming-based default reasoning approaches which are not using negation-as-failure in their object language. Instead, default reasoning is modelled by rules and a priority relation among them. Historically the first logic in this class was Defeasible logic. In this paper we will study its relationship to other approaches which also rely on the idea of using logic rules and priorities. In particular we will study sceptical LPwNF, courteous logic programs, and priority logic.
We prove two properties of logic programs under the answer set semantics that may be useful in connection with applications of logicprogramming to representing causality and to planning. One theorem is about the use ...
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ISBN:
(纸本)3540667490
We prove two properties of logic programs under the answer set semantics that may be useful in connection with applications of logicprogramming to representing causality and to planning. One theorem is about the use of disjunctive rules to express that an atom is exogenous. the other provides an alternative way of expressing that a plan does not include concurrently executed actions.
We investigate the problem of reasoning in nonmonotonic extensions of first-order logic. In particular, we study reasoning in first-order MKNF, the modal logic of minimal knowledge and negation as failure introduced b...
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ISBN:
(纸本)3540667490
We investigate the problem of reasoning in nonmonotonic extensions of first-order logic. In particular, we study reasoning in first-order MKNF, the modal logic of minimal knowledge and negation as failure introduced by Lifschitz. MKNF can be considered as a unifying framework for several nonmonotonic formalisms, including default logic, autoepistemic logic, circumscription, and logicprogramming. By suitably extending deduction methods for propositional nonmonotonic logics, we define techniques for reasoning in significant subsets of first-order MKNF, which allow for characterizing decidable fragments of first-order nonmonotonic modal logics. Due to the expressive abilities of MKNF, such techniques can be seen as general reasoning methods for several nonmonotonic formalisms based on first-order logic. We also analyze the relationship between such decidable fragments of MKNF and disjunctive Datalog.
Despite the obvious relevance of plausible reasoning to real-world problem solving, nonmonotonic logics are rarely used in commercial applications or large- scale commonsense reasoning systems. this is largely because...
ISBN:
(纸本)3540667490
Despite the obvious relevance of plausible reasoning to real-world problem solving, nonmonotonic logics are rarely used in commercial applications or large- scale commonsense reasoning systems. this is largely because few efficient algorithms and tools have thus far been developed.
We show how a class of domains written in the Language E, a high level language for reasoning about actions, narratives and. change, can be translated into the argumentation framework of logicprogramming without Nega...
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ISBN:
(纸本)3540667490
We show how a class of domains written in the Language E, a high level language for reasoning about actions, narratives and. change, can be translated into the argumentation framework of logicprogramming without Negation as Failure (LPwNF). this translation enables us 1) to understand default persistence as captured by various temporal reasoning frameworks in a simple and natural way, by assigning higher priority to information about effects of later actions over effects of earlier actions;2) to develop an argumentation-based computational model for this type of reasoning in logicprogramming goal-driven style.
this paper continues the line of research on representing actions, on the automation of commonsense reasoning and on planning that deals with causal theories and with action language C. We show here that many of the i...
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ISBN:
(纸本)3540667490
this paper continues the line of research on representing actions, on the automation of commonsense reasoning and on planning that deals with causal theories and with action language C. We show here that many of the ideas developed in that work can be formulated in terms of logic programs under the answer set semantics, without mentioning causal theories. the translations from C into logicprogrammingthat we investigate serve as a basis for the use of systems for computing answer sets to reason about action domains described in C and to generate plans in such domains.
We present a new approach to reasoning with default logicthat aims at Reiter's original approach, whenever there is no source for incoherence. We accomplish this by shifting the emphasis from the application of i...
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ISBN:
(纸本)3540667490
We present a new approach to reasoning with default logicthat aims at Reiter's original approach, whenever there is no source for incoherence. We accomplish this by shifting the emphasis from the application of individual default rules to that of the joint application of a default rule together with rules supporting this application. this allows for reasoning in an incremental yet compositional fashion, without giving up the expressiveness needed for knowledge representation. Technically, our approach differs from others in that it guarantees the existence of extensions without requiring semi-monotonicity.
In general, the set of stable models of a recursive propositional logic program can be quite complex. For example, it follows from results of Marek, Nerode, and Remmel [8] that there exists finite predicate logic prog...
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ISBN:
(纸本)3540667490
In general, the set of stable models of a recursive propositional logic program can be quite complex. For example, it follows from results of Marek, Nerode, and Remmel [8] that there exists finite predicate logic programs and recursive propositional logic programs which have stable models but no hyperarithmetic stable models. In this paper, we shall define several conditions which ensure that recursive logic program has astable model which is recursive.
this paper introduces techniques for updating knowledge bases represented in extended logic programs. three different types of updates, view updates, theory updates, and inconsistency removal, are considered. We formu...
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ISBN:
(纸本)3540667490
this paper introduces techniques for updating knowledge bases represented in extended logic programs. three different types of updates, view updates, theory updates, and inconsistency removal, are considered. We formulate these updates through abduction, and provide methods for computing them with update programs. An update program is an extended logic program which specifies changes on abductive hypotheses, then updates are computed by the U-minimal answer sets of an update program. the proposed technique provides a uniform framework for these different types of updates, and each update is computed using existing procedures of logicprogramming.
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