| 1. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Approximate Databases and Query Techniques for Agents with Heterogenous Perceptual Capabilities
- 2004
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Ingår i: Proceedings of the 7th International Conference on Information Fusion. - Mountain View, CA : ISIF. - 917056115X ; , s. 175-182
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a framework that provides software and robotic agents with the ability to ask approximate questions to each other in the context of heterogeneous and contextually limited perceptual capabilities. The framework focuses on situations where agents have varying ability to perceive their environments. These limitations on perceptual capability are formalized using the idea of tolerance spaces. It is assumed that each agent has one or more approximate databases where approximate relations are represented using intuitions from rough set theory. It is shown how sensory and other limitations can be taken into account when constructing approximate databases for each respective agent. Complex relations inherit the approximativeness inherent in the sensors and primitive relations used in their definitions. Agents then query these databases and receive answers through the filters of their perceptual limitations as represented by tolerance spaces and approximate queries. The techniques used are all tractable.
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| 2. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Approximative Query Techniques for Agents with Heterogeneous Ontologies and Perceptive Capabilities
- 2004
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Ingår i: Proceedings of the 9th International Conference on the Principles of Knowledge Representation and Reasoning. - Menlo Park, California : AAAI Press. - 9781577351993 ; , s. 459-468
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a framework that provides software and robotic agents with the ability to ask approximate questions to each other in the context of heterogeneous ontologies and heterogeneous perceptive capabilities.The framework combines the use of logic-based techniques with ideas from approximate reasoning. Initial queries by an agent are transformed into approximate queries using weakest sufficient and strongest necessary conditions on the query and are interpreted as lower and upper approximations on the query. Once the base communication ability is provided, the framework is extended to situations where there is not only a mismatch between agent ontologies, but the agents have varying ability to perceive their environments. This will affect each agent’s ability to ask and interpret results of queries. Limitations on perceptive capability are formalized using the idea of tolerance spaces.
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| 3. |
- Doherty, Patrick, 1957-, et al.
(författare)
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CAKE : A computer aided knowledge engineering technique.
- 2002
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Ingår i: Proceedings of the 15th European Conference on Artificial Intelligence,2002. - : IOS Press. ; , s. 220-224
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Konferensbidrag (refereegranskat)abstract
- Introduction: Logic engineering often involves the development of modeling tools and inference mechanisms (both standard and non-standard) which are targeted for use in practical applications where expressiveness in representation must be traded off for efficiency in use. Some representative examples of such applications would be the structuring and querying of knowledge on the semantic web, or the representation and querying of epistemic states used with softbots, robots or smart devices. In these application areas, declarative representations of knowledge enhance the functionality of such systems and also provide a basis for insuring the pragmatic properties of modularity and incremental composition. In addition, the mechanisms developed should be tractable, but at the same time, expressive enough to represent such aspects as default reasoning, or approximate or incomplete representations of the environments in which the entities in question are embedded or used, be they virtual or actual. [...]
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| 4. |
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| 5. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Computing circumscription revisited.
- 1995
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Ingår i: Proceedings of the 14th International Joint Conference on Artificial Intelligence (IJCAI). - 9781558603639 ; , s. 1502-1508
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Konferensbidrag (refereegranskat)
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| 6. |
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| 7. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Computing strongest necessary and weakest sufficient conditions of first-order formulas
- 2001
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Ingår i: 17th International Joint Conference on Artificial Intelligence,2001. - San Francisco, CA, USA : Morgan Kaufmann Publishers Inc.. - 1558608125 - 9781558608122 ; , s. 145-151
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Konferensbidrag (refereegranskat)abstract
- A technique is proposed for computing the weakest sufficient (wsc) and strongest necessary (snc) conditions for formulas in an expressive fragment of first-order logic using quantifier elimination techniques. The efficacy of the approach is demonstrated by using the techniques to compute snc's and wsc's for use in agent communication applications, theory approximation and generation of abductive hypotheses. Additionally, we generalize recent results involving the generation of successor state axioms in the propositional situation calculus via snc's to the first-order case. Subsumption results for existing approaches to this problem and a re-interpretation of the concept of forgetting as a process of quantifier elimination are also provided.
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| 8. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Defaults as first-class citizens
- 1992
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Ingår i: Proceedings of the 22nd International Symposium on Multiple-Valued Logic (SMVL). - : IEEE Computer Society. - 0818626801 ; , s. 146-154
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Konferensbidrag (refereegranskat)abstract
- A nonmonotonic logic with explicit defaults, NML3, is presented. It is characterized by the following features: (1) the use of the strong Kleene three-valued logic as a basis; (2) the addition of an explicit default operator which enables distinguishing tentative conclusions from ordinary conclusions in the object language; and (3) the use of the idea of preferential entailment to generate nonmonotonic behavior. The central feature of the formalism, the use of an explicit default operator with a model-theoretic semantics based on the notion of a partial interpretation, distinguishes NML3 from most previous formalisms. By capitalizing on the distinction between tentative and ordinary conclusions, NML3 provides increased expressibility in comparison to many of the standard nonmonotonic formalisms and greater flexibility in the representation of subtle aspects of default reasoning. This is shown through examples.
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| 9. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Efficient reasoning using the local closed-world assumption
- 2000
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Ingår i: Proceedings of the 9th International Conference on Artificial Intelligence: Methodology, Systems and Applications (AIMSA). - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783540410447 - 9783540453314 ; , s. 49-58
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Konferensbidrag (refereegranskat)abstract
- We present a sound and complete, tractable inference method for reasoning with localized closed world assumptions (LCWA’s) which can be used in applications where a reasoning or planning agent can not assume complete information about planning or reasoning states. This Open World Assumption is generally necessary in most realistic robotics applications. The inference procedure subsumes that described in Etzioni et al [9], and others. In addition, it provides a great deal more expressivity, permitting limited use of negation and disjunction in the representation of LCWA’s, while still retaining tractability. The ap- proach is based on the use of circumscription and quantifier elimination techniques and inference is viewed as querying a deductive database. Both the preprocessing of the database using circumscription and quan- tifier elimination, and the inference method itself, have polynomial time and space complexity.
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| 10. |
- Doherty, Patrick, 1957-, et al.
(författare)
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Explaining explanation closure
- 1996
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Ingår i: Proceedings of the 9th International Symposium on Methodologies for Intelligent Systems,1996. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 3540612866 ; , s. 521-530
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Konferensbidrag (refereegranskat)abstract
- Recently, Haas, Schubert, and Reiter, have developed an alternative approach to the frame problem which is based on the idea of using explanation closure axioms. The claim is that there is a monotonic solution for characterizing nonchange in serial worlds with fully specified actions, where one can have both a succinct representation of frame axioms and an effective proof theory for the characterization. In the paper, we propose a circumscriptive version of explanation closure, PMON, that has an effective proof theory and works for both context dependent and nondeterministic actions. The approach retains representational succinctness and a large degree of elaboration tolerance, since the process of generating closure axioms is fully automated and is of no concern to the knowledge engineer. In addition, we argue that the monotonic/nonmonotonic dichotomy proposed by others is not as sharp as previously claimed and is not fully justified.
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