| 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)
-
Approximation Transducers and Trees : A Technique for Combining Rough and Crisp Knowledge
- 2004
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Ingår i: Rough-Neural Computing: Techniques for Computing with Words. - Berlin, Heidelberg, New York : Springer. - 9783540430599 - 3540430598 ; , s. 189-218
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Soft computing comprises various paradigms dedicated to approximately solving real-world problems, e.g., in decision making, classification or learning; among these paradigms are fuzzy sets, rough sets, neural networks, and genetic algorithms.It is well understood now in the soft computing community that hybrid approaches combining various paradigms provide very promising attempts to solving complex problems. Exploiting the potential and strength of both neural networks and rough sets, this book is devoted to rough-neurocomputing which is also related to the novel aspect of computing based on information granulation, in particular to computing with words. It provides foundational and methodological issues as well as applications in various fields.
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| 3. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
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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| 4. |
- 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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| 5. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
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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| 6. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
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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| 7. |
- Doherty, Patrick, 1957-, et al.
(författare)
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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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| 8. |
- Doherty, Patrick, 1957-, et al.
(författare)
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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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| 9. |
- Doherty, Patrick, 1957-, et al.
(författare)
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The PMA and relativizing minimal change for action update
- 2000
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Ingår i: Fundamenta Informaticae. - : IOS Press. - 0169-2968 .- 1875-8681. ; 44:1-2, s. 95-131
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Tidskriftsartikel (refereegranskat)abstract
- Recently, a great deal of progress has been made using nonmonotonic temporal logics to formalize reasoning about action and change. In particular, much focus has been placed on the proper representation of non-deterministic actions and the indirect effects of actions. For the latter the use of causal or fluent dependency rule approaches has been dominant. Although much recent effort has also been spent applying the belief revision/update (BR/U) approach to the action and change domain, there has been less progress in dealing with nondeterministic update and indirect effects represented as integrity constraints. We demonstrate that much is to be gained by cross-fertilization between the two paradigms and we show this in the following manner. We first propose a generalization of the PMA, called the modified MPMA which uses intuitions from the TL paradigm to permit representation of nondeterministic update and the use of integrity constraints interpreted as causal or fluent dependency rules. We provide several syntactic characterizations of MPMA, one of which is in terms of a simple temporal logic and provide a representation theorem showing equivalence between the two. In constructing the MPMA, we discovered a syntactic anomaly which we call the redundant atom anomaly that many TL approaches suffer from. We provide a method for avoiding the problem which is equally applicable across paradigms. We also describe a syntactic characterization of MPMA in terms of Dijkstra semantics. We set up a framework for future generalization of the BR/U approach and conclude with a formal comparison of related approaches.
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| 10. |
- Doherty, Patrick, 1957-, et al.
(författare)
-
Tolerance Spaces and Approximative Representational Structures
- 2003
-
Ingår i: Proceedings of the 26th German Conference on Artificial Intelligence (KI). - Berlin, Heidelberg : Springer. ; , s. 475-489
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Konferensbidrag (refereegranskat)abstract
- In traditional approaches to knowledge representation, notions such as tolerance measures on data, distance between objects or individuals, and similarity measures between primitive and complex data structures are rarely considered. There is often a need to use tolerance and similarity measures in processes of data and knowledge abstraction because many complex systems which have knowledge representation components such as robots or software agents receive and process data which is incomplete, noisy, approximative and uncertain. This paper presents a framework for recursively constructing arbitrarily complex knowledge structures which may be compared for similarity, distance and approximativeness. It integrates nicely with more traditional knowledge representation techniques and attempts to bridge a gap between approximate and crisp knowledge representation. It can be viewed in part as a generalization of approximate reasoning techniques used in rough set theory. The strategy that will be used is to define tolerance and distance measures on the value sets associated with attributes or primitive data domains associated with particular applications. These tolerance and distance measures will be induced through the different levels of data and knowledge abstraction in complex representational structures. Once the tolerance and similarity measures are in place, an important structuring generalization can be made where the idea of a tolerance space is introduced. Use of these ideas is exemplified using two application domains related to sensor modeling and communication between agents.
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