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Natural 3valued Logics  Characterization and Proof Theory
 Journal of Symbolic Logic
, 1991
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Representing Uncertainty in Simple Planners
 In Proceedings of the Fourth International Conference on Principles of Knowledge Representation and Reasoning
, 1994
"... In this paper, we present an analysis of planning with uncertain information regarding both the state of the world and the effects of actions using a Strips or (propositional) Adlstyle representation [4, 17]. We provide formal definitions of plans under incomplete information and conditional ..."
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In this paper, we present an analysis of planning with uncertain information regarding both the state of the world and the effects of actions using a Strips or (propositional) Adlstyle representation [4, 17]. We provide formal definitions of plans under incomplete information and conditional plans, and describe Plinth, a conditional linear planner based on these definitions. We also clarify the definition of the term "conditional action, " which has been variously used to denote actions with contextdependent effects and actions with uncertain outcomes. We show that the latter can, in theory, be viewed as a special case of the former but that to do so requires one to sacrifice the simple, singlemodel representation for one which can distinguish between a proposition and beliefs about that proposition. 1
Natural 3valued logics—characterization and proof theory
 J. of Symbolic Logic
, 1991
"... Manyvalued logics in general and 3valued logic in particular is an old subject which had its beginning in the work of Lukasiewicz [Luk]. Recently there is a revived interest in this topic, both for its own sake (see, e.g. [Ho]), and also because of its potential applications in several areas of co ..."
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Cited by 12 (0 self)
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Manyvalued logics in general and 3valued logic in particular is an old subject which had its beginning in the work of Lukasiewicz [Luk]. Recently there is a revived interest in this topic, both for its own sake (see, e.g. [Ho]), and also because of its potential applications in several areas of computer science, like:
Logic engineering in medicine
 The Knowledge Engineering Review
, 1995
"... The safetycritical nature of the application of knowledgebased systems to the field of medicine, demands the adoption of reliable engineering principles with a solid foundation for their construction. Logical languages with their inherent, precise notions of consistency, soundness and completeness ..."
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Cited by 11 (6 self)
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The safetycritical nature of the application of knowledgebased systems to the field of medicine, demands the adoption of reliable engineering principles with a solid foundation for their construction. Logical languages with their inherent, precise notions of consistency, soundness and completeness offer such a foundation, thus promoting scrutinous engineering of medical knowledge. Moreover, logic techniques provide a powerful means for getting insight into the structure and meaning of medical knowledge used in medical problem solving. Unfortunately, logic is currently only used on a small scale for building practical medical knowledgebased systems. In this paper, the various approaches proposed in the literature are reviewed, and related to different types of knowledge and problem solving employed in the medical field. The appropriateness of logic for building medical knowledgebased expert systems is further motivated.
Toward a Model Theory of Actions: How Agents do it in Branching Time
 Computational Intelligence
, 1998
"... A clear understanding and formalization of actions is essential to computing, and especially so to reasoning about and constructing intelligent agents. Several approaches have been proposed over the years. However, most approaches concentrate on the causes and effects of actions, but do not give gen ..."
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A clear understanding and formalization of actions is essential to computing, and especially so to reasoning about and constructing intelligent agents. Several approaches have been proposed over the years. However, most approaches concentrate on the causes and effects of actions, but do not give general characterizations of actions themselves. A useful formalization of actions would be based on a general, possibly nondiscrete, model of time that allows branching (to capture agents' choices). A desirable formalization would also allow actions to be of arbitrary duration and would permit multiple agents to act concurrently. We develop a branchingtime framework that allows great flexibility in how time and action are modeled. We motivate and formalize several coherence constraints on our models, which capture some nice intuitions and validate some useful inferences relating actions with time. 1 Introduction Over the years, actions and time have garnered much research attent...
Heuristic Reasoning and Relative Incompleteness
, 1992
"... In this paper an approach is presented in which heurkstic reasoning is interpreted as strategic reasoning. This type of reasoning enables one to den’ve which hypothesis to investigate, and which observable information to acquire next (to be able to verify the chosen hypothesis). A compositional arch ..."
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In this paper an approach is presented in which heurkstic reasoning is interpreted as strategic reasoning. This type of reasoning enables one to den’ve which hypothesis to investigate, and which observable information to acquire next (to be able to verify the chosen hypothesis). A compositional architecture for reasoning systems that perform such heuristic reasoning is introduced, called SIX (for Strategic Interactive expert systems). This compositional architecture enables user interaction at strategic level. It is formally specified in the specification framework DESIRE (DEsign and Specification of Interacting REsoning modules). We show that this reasoning method can adequately be applied to deal with relative incompleteness in domains that have a (layered) empirical basis. A logical analysis of domains is presented making these concepts more precise. A theorem is presented stating that a domain has an empirical basis if and only if a decisive knowledge base is possible. Moreover, a simple criterion is given to test whether or not a domain is empirically founded: implicit definability of hypotheses in terms of observables.
Evaluating Reasoning Systems
, 2006
"... A review of the literature on evaluating reasoning systems reveals that it is a very broad area with wide variation in depth and breadth of research on metrics and tests. Consolidation is hampered by nonstandard terminology, differing methodologies, scattered application domains, unpublished algorit ..."
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A review of the literature on evaluating reasoning systems reveals that it is a very broad area with wide variation in depth and breadth of research on metrics and tests. Consolidation is hampered by nonstandard terminology, differing methodologies, scattered application domains, unpublished algorithmic details, and the effects of domain content and context on the choice of metric and tests. The field of information metrology, which applies to reasoning as a kind of information processing, is still emerging from ad hoc experience in evaluating narrow kinds of information systems. This report begins to bring order to the area by categorizing reasoning systems according to their capabilities. The characteristics of each category can be used as a basis for evaluating and testing reasoning systems claiming to be in that category. Capabilities are analyzed along several dimensions, including representation languages, inference, and user and software interfaces. The report groups representation languages by their relation to firstorder logic, and modeltheoretic properties, such as soundness and completeness. Inference procedures are divided into deduction, induction, abduction, and analogical reasoning. Capabilities of user and software interfaces are described as they apply to
An algebraic approach to rule based expert systems
"... Abstract This article presents a survey of the authors ’ research on knowledge extraction and verification of Rule Based Expert Systems (RBES) using algebraic inference engines and based on Gröbner bases theory. A shell, including a graphic user interface and inference engines for different logics ..."
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Abstract This article presents a survey of the authors ’ research on knowledge extraction and verification of Rule Based Expert Systems (RBES) using algebraic inference engines and based on Gröbner bases theory. A shell, including a graphic user interface and inference engines for different logics (both classic and modal multivalued) as well as in different computer algebra systems, is also presented here. The shell distinguishes three levels: at the lower level, we provide the computer algebra system code of the algebraic inference engines; at the intermediate level, the RBES developer has to detail the rules and integrity constraints of a certain RBES; and, finally, at the upper level, the final user deals with a simple GUI, where he can perform knowledge extraction or verify the RBES, after choosing the logic and inputing a consistent set of facts. We believe that this shell can be really useful for teaching and quick RBES design. Una aproximación algebraica a los sistemas expertos basados en reglas Resumen. Este artı́culo presenta una panorámica de la lı́nea de investigación de los autores en extracción de conocimiento y verificación de Sistemas Expertos Basados en Reglas (RBES) usando motores de inferencia algebraicos y basada en la teorı́a de bases de Gröbner. Se presenta también una shell, que incluye una interfaz gráfica de usuario y motores de inferencia para distintas lógicas (tanto clásicas como
The Knowledge Engineering Review An Al view of the treatment of uncertainty
"... This paper reviews many of the very varied concepts of uncertainty used in AI. Because of their great popularity and generality "parallel certainty inference " techniques, socalled, are prominently in the foreground. We illustrate and comment in detail on three of these techniques; Bayes ..."
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This paper reviews many of the very varied concepts of uncertainty used in AI. Because of their great popularity and generality "parallel certainty inference " techniques, socalled, are prominently in the foreground. We illustrate and comment in detail on three of these techniques; Bayes ' theory (section 2); DempsterShafer theory (section 3); Cohen's model of endorsements (section 4), and give an account of the debate that has arisen around each of them. Techniques of a different kind (such as Zadeh's fuzzysets, fuzzylogic theory, and the use of nonstandard logics and methods that manage uncertainty without explicitly dealing with it) may be seen in the background (section 5). The discussion of technicalities is accompanied by a historical and philosophical excursion on the nature and the use of uncertainty (section 1), and by a brief discussion of the problem of choosing an adequate AI approach to the treatment of uncertainty (section 6). The aim of the paper is to highlight the complex nature of uncertainty and to argue for an openminded attitude towards its representation and use. In this spirit the pros and cons of uncertainty treatment techniques are presented in order to reflect the various uncertainty types. A guide to the literature in the field, and an extensive bibliography are appended.
Gentzentype Refutation Systems for ThreeValued Logics ⋆
"... Abstract. While the purpose of a conventional proof calculus is to axiomatise the set of valid sentences of a given logic, a refutation system, or complementary calculus, is concerned with axiomatising the invalid sentences. Instead of exhaustively searching for counter models for some sentence, ref ..."
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Abstract. While the purpose of a conventional proof calculus is to axiomatise the set of valid sentences of a given logic, a refutation system, or complementary calculus, is concerned with axiomatising the invalid sentences. Instead of exhaustively searching for counter models for some sentence, refutation systems establish invalidity by deduction and thus in a purely syntactic way. Such systems are relevant not only for prooftheoretic reasons but also for realising deductive systems for nonmonotonic logics. In this paper, we introduce Gentzentype refutation systems for two basic threevalued logics that allow to embed wellknown threevalued logics relevant for AI and logic programming like that of Kleene, Łukasiewicz, Gödel, as well as threevalued paraconsistent logics. As an application of our calculus, we provide derived rules for Gödel’s threevalued logic, allowing to decide strong equivalence of logic programs under the answerset semantics. 1