| 21. |
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| 22. |
- Doherty, Patrick, 1957-, et al.
(författare)
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General domain circumscription and its effective reductions.
- 1998
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Ingår i: Fundamenta Informaticae. - : IOS Press. - 0169-2968 .- 1875-8681. ; 36:1, s. 23-55
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Tidskriftsartikel (refereegranskat)abstract
- We first define general domain circumscription (GDC) and provide it with a semantics. GDC subsumes existing domain circumscription proposals in that it allows varying of arbitrary predicates, functions, or constants, to maximize the minimization of the domain of a theory. We then show that for the class of semi-universal theories without function symbols, that the domain circumscription of such theories can be constructively reduced to logically equivalent first-order theories by using an extension of the DLS algorithm, previously proposed by the authors for reducing second-order formulas. We also show that for a certain class of domain circumscribed theories, that any arbitrary second-order circumscription policy applied to these theories is guaranteed to be reducible to a logically equivalent first-order theory. In the case of semi-universal theories with functions and arbitrary theories which are not separated, we provide additional results, which although not guaranteed to provide reductions in all cases, do provide reductions in some cases. These results are based on the use of fixpoint reductions.
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| 23. |
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| 24. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
General domain circumscription and its first-order reduction.
- 1996
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Ingår i: Proceedings of the 1st International Conference on Formal and Applied Practical Reasoning (FAPR). - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783540613138 ; , s. 93-109
-
Konferensbidrag (refereegranskat)abstract
- We first define general domain circumscription (GDC) and provide it with a semantics. GDC subsumes existing domain circumscription proposals in that it allows varying of arbitrary predicates, functions, or constants, to maximize the minimization of the domain of a theory We then show that for the class of semi-universal theories without function symbols, that the domain circumscription of such theories can be constructively reduced to logically equivalent first-order theories by using an extension of the DLS algorithm, previously proposed by the authors for reducing second-order formulas. We also isolate a class of domain circumscribed theories, such that any arbitrary second-order circumscription policy applied to these theories is guaranteed to be reducible to a logically equivalent first-order theory. In the case of semi-universal theories with functions and arbitrary theories which are not separated, we provide additional results, which although not guaranteed to provide reductions in all cases, do provide reductions in some cases. These results are based on the use of fixpoint reductions.
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| 25. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
Information Granules for Intelligent Knowledge Structures
- 2003
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Ingår i: Proceedings of the 9th International Conference on Rough Sets, Fuzzy Sets, Data Mining and Granular Computing (RSFDGrC). - : Springer. - 9783540140405 ; , s. 405-412
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Konferensbidrag (refereegranskat)abstract
- The premise of this paper is that the acquisition, aggregation, merging and use of information requires some new ideas, tools and techniques which can simplify the construction, analysis and use of what we call ephemeral knowledge structures. Ephemeral knowledge structures are used and constructed by granular agents. Each agent contains its own granular information structure and granular information structures of agents can be combined together. The main concept considered in this paper is an information granule. An information granule is a concise conceptual unit that can be integrated into a larger information infrastructure consisting of other information granules and dependencies between them. The novelty of this paper is that it provides a concise and formal definition of a particular view of information granule and its associated operators, as required in advanced knowledge representation applications.
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| 26. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
Knowledge Representation Techniques. : a rough set approach
- 2006
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- The basis for the material in this book centers around a long term research project with autonomous unmanned aerial vehicle systems. One of the main research topics in the project is knowledge representation and reasoning. The focus of the research has been on the development of tractable combinations of approximate and nonmonotonic reasoning systems. The techniques developed are based on intuitions from rough set theory. Efforts have been made to take theory into practice by instantiating research results in the context of traditional relational database or deductive database systems. This book contains a cohesive, self-contained collection of many of the theoretical and applied research results that have been achieved in this project and for the most part pertain to nonmonotonic and approximate reasoning systems developed for an experimental unmanned aerial vehicle system used in the project. This book should be of interest to the theoretician and applied researcher alike and to autonomous system developers and software agent and intelligent system developers.
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| 27. |
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| 28. |
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| 29. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
On mutual understanding among communicating agents
- 2003
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Ingår i: Proceedings of the International Workshop on Formal Approaches to Multi-Agent Systems (FAMAS). ; , s. 83-97
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Konferensbidrag (refereegranskat)
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| 30. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
Similarity, approximations and vagueness
- 2005
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Ingår i: Proceedings of the 10th International Conference on Rough Sets, Fuzzy Sets, Data Mining, and Granular Computing (RSFDGrC). - Berlin, Heidelberg : Springer. - 3540286535 ; , s. 541-550
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Konferensbidrag (refereegranskat)abstract
- The relation of similarity is essential in understanding and developing frameworks for reasoning with vague and approximate concepts. There is a wide spectrum of choice as to what properties we associate with similarity and such choices determine the nature of vague and approximate concepts defined in terms of these relations. Additionally, robotic systems naturally have to deal with vague and approximate concepts due to the limitations in reasoning and sensor capabilities. Halpern [1] introduces the use of subjective and objective states in a modal logic formalizing vagueness and distinctions in transitivity when an agent reasons in the context of sensory and other limitations. He also relates these ideas to a solution to the Sorities and other paradoxes. In this paper, we generalize and apply the idea of similarity and tolerance spaces [2,3,4,5], a means of constructing approximate and vague concepts from such spaces and an explicit way to distinguish between an agent’s objective and subjective states. We also show how some of the intuitions from Halpern can be used with similarity spaces to formalize the above-mentioned Sorities and other paradoxes.
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