the BQM1 system extends deductive database technology with knowledge structuring capabilities to provide an advanced environment for the development of data and knowledge-based applications. the system relies on a kno...
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ISBN:
(纸本)0818673125
the BQM1 system extends deductive database technology with knowledge structuring capabilities to provide an advanced environment for the development of data and knowledge-based applications. the system relies on a knowledge representation language that combines the declarativeness of logicprogramming withthe notions of object, inheritance with exceptions, and message passing. Exceptions are supported by allowing rules with negated heads. the use of exceptions inside the inheritance mechanism makes the language inherently nonmonotonic. the paper describes BQM focusing on boththe language and the implementation techniques. An informal overview of the language is first given. then, a number of techniques for efficient query evaluation are presented. these techniques significantly extend 'traditional' deductive database query evaluation strategies to deal withnonmonotonicreasoning. A description of the architecture of the current prototype of the BQM system is also given.
Reiter's default logic formalizes nonmonotonicreasoning using default assumptions. the semantics of a given instance of default logic is based on a fixpoint equation defining an extension. three different reasoni...
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ISBN:
(纸本)9783540721994
Reiter's default logic formalizes nonmonotonicreasoning using default assumptions. the semantics of a given instance of default logic is based on a fixpoint equation defining an extension. three different reasoning problems arise in the context of default logic, namely the existence of an extension, the presence of a given formula in an extension, and the occurrence of a formula in all extensions. Since the end of 1980s, several complexity results have been published concerning these default reasoning problems for different syntactic classes of formulas. We derive in this paper a complete classification of default logicreasoning problems by means of universal algebra tools using Post's clone lattice. In particular we prove a trichotomy theorem for the existence of an extension, classifying this problem to be either polynomial, NP-complete, or Sigma P-2-complete, depending on the set of underlying Boolean connectives. We also prove similar trichotomy theorems for the two other algorithmic problems in connection with default logicreasoning.
the program composition approach can be fruitfully applied to combine general logic programs, i.e, logic programs possibly containing negative premises. We show how the introduction of a basic set of (meta-level) comp...
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ISBN:
(纸本)3540632557
the program composition approach can be fruitfully applied to combine general logic programs, i.e, logic programs possibly containing negative premises. We show how the introduction of a basic set of (meta-level) composition operations over general programs increases the knowledge representation capabilities of logicprogramming for non-monotonic reasoning. Examples of modular programming, hierarchical reasoning, constraints, and rules with exceptions will be illustrated. the semantics of programs and program compositions is defined in terms of three-valued logic [15]. the computational interpretation of program compositions is formalised by an equivalence preserving syntactic transformation of arbitrary program compositions into standard general programs.
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.
the formalism of nonmonotonic causal theories (Ciunchiglia, Lee, Lifschitz, McCain, Turner, 2004) provides a general-purpose formalism for nonmonotonicreasoning and knowledge representation, as well as a higher level...
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ISBN:
(纸本)3540285385
the formalism of nonmonotonic causal theories (Ciunchiglia, Lee, Lifschitz, McCain, Turner, 2004) provides a general-purpose formalism for nonmonotonicreasoning and knowledge representation, as well as a higher level, special-purpose notation, the action language C+, for specifying and reasoning about the effects of actions and the persistence ('inertia') of facts over time. In this paper we investigate some logical properties of these formalisms. there are two motivations. From the technical point of view, we seek to gain additional insights into the properties of the languages when viewed as a species of conditional logic. From the practical point of view, we are seeking to find conditions under which two different causal theories, or two different action descriptions in C+, can be said to be equivalent, withthe further aim of helping to decide between alternative formulations when constructing practical applications.
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.
An extension of DLV by aggregates to simplify the encoding of the frequently occuring concepts is discussed. DLV is an efficient Answer Set programming (ASP) system which can implement the answer set semantics with va...
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ISBN:
(纸本)354020721X
An extension of DLV by aggregates to simplify the encoding of the frequently occuring concepts is discussed. DLV is an efficient Answer Set programming (ASP) system which can implement the answer set semantics with various language extensions. the semantics of programs without aggregates is provided in BLR00 as an extension of the classical answer set semantics given in GL91. the strong point of DLV is its robust and efficient implementation, which integrates algorithms and heuristics from the field of nonmonotic reasoning.
A recently proposed module system for answer set programming is generalized for the input language of the SMODELS system. To show that the stable model semantics is compositional and modular equivalence is a congruenc...
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ISBN:
(纸本)9783540721994
A recently proposed module system for answer set programming is generalized for the input language of the SMODELS system. To show that the stable model semantics is compositional and modular equivalence is a congruence for composition of SMODELS program modules, a general translation-based scheme for introducing syntactic extensions of the module system is presented. A characterization of the compositionality of the semantics is used as an alternative condition for module composition, which allows compositions of modules even in certain cases with positive recursion between the modules to be composed.
reasoning on Constraint Handling Rules (CHR) programs and their executional behaviour is often ad-hoc and outside of a formal system. this is a pity, because CHR subsumes a wide range of important automated reasoning ...
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ISBN:
(纸本)9783540721994
reasoning on Constraint Handling Rules (CHR) programs and their executional behaviour is often ad-hoc and outside of a formal system. this is a pity, because CHR subsumes a wide range of important automated reasoning services. Mapping CHR to Transaction logic (TR) combines CHR rule specification, CHR rule application, and reasoning on CHR programs and CHR derivations inside one formal system which is executable. this new TR semantics obviates the need for disjoint declarative and operational semantics.
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