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A Computationally Grounded Logic of Visibility, Perception, and Knowledge
, 2001
"... VSK logic is a family of multimodal logics for reasoning about the information properties of computational agents situated in some environment. Using VSK logic, we can represent what is objectively true of the environment, the information that is visible,orknowable about the environment, informat ..."
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Cited by 17 (1 self)
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VSK logic is a family of multimodal logics for reasoning about the information properties of computational agents situated in some environment. Using VSK logic, we can represent what is objectively true of the environment, the information that is visible,orknowable about the environment, information the agent perceives of the environment, and finally, information the agent actually knows about the environment. The semantics of VSK logic are given in terms of a general, automatalike model of agents. In this paper, we prove completeness for an axiomatisation of VSK logic, and present correspondence results for a number of VSK interaction axioms in terms of the architectural properties of the agent that they represent. The completeness proof is novel in that we are able to prove completeness with respect to the automatalike semantics. In this sense, VSK logic is said to be computationally grounded. We give an example to illustrate the formalism, and present conclusions and issues for further work.
Knowledge provenance: An approach to modeling and maintaining the evolution and validity of knowledge
, 2003
"... www.eil.utoronto.ca ..."
A New Method for Bounding the Complexity of Modal Logics
, 1997
"... . We present a new prooftheoretic approach to bounding the complexity of the decision problem for propositional modal logics. We formalize logics in a uniform way as sequent systems and then restrict the structural rules for particular systems. This, combined with an analysis of the accessibility r ..."
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Cited by 12 (2 self)
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. We present a new prooftheoretic approach to bounding the complexity of the decision problem for propositional modal logics. We formalize logics in a uniform way as sequent systems and then restrict the structural rules for particular systems. This, combined with an analysis of the accessibility relation of the corresponding Kripke structures, yields decision procedures with bounded space requirements. As examples we give O(n log n) space procedures for the modal logics K and T. 1 Introduction We present a new prooftheoretic approach to bounding the complexity of the decision problem for propositional modal logics. We formalize logics in a uniform way as cutfree labelled sequent systems and then restrict the structural rules for particular systems. This, combined with an analysis of the accessibility relation of the corresponding Kripke structures, yields decision procedures with space requirements that are easily bounded. As examples we give O(n log n) space decision procedures f...
Contextdriven disambiguation in ontology elicitation
 Context and Ontologies: Theory, Practice, and Applications. Proc. of the 1st Context and Ontologies Workshop, AAAI/IAAI 2005
, 2005
"... Ontologies represent rich semantics in a lexical way. Lexical labels are used to identify concepts and relationships, though there is no bijective mapping between them. Phenomenons such as synonyms and homonyms exemplify this, and can result in frustrating misunderstanding and ambiguity. In the elic ..."
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Cited by 12 (5 self)
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Ontologies represent rich semantics in a lexical way. Lexical labels are used to identify concepts and relationships, though there is no bijective mapping between them. Phenomenons such as synonyms and homonyms exemplify this, and can result in frustrating misunderstanding and ambiguity. In the elicitation and application of ontologies, the meaning of the ontological knowledge is dependent on the context. We consider the role of context in ontology elicitation by introducing context in a concept definition server for ontology representation. We also adopt other features of context found in literature, such as packaging of knowledge, aligning elements of different contexts, and reasoning about contexts. Finally, we illustrate contextdriven ontology elicitation with a real world case study.
Formalising Abilities and Opportunities of Agents
 Fundamenta Informaticae
, 1998
"... We present a formal system to reason about and specify the behavior of multiple intelligent artificial agents. Essentially, each agent can perform certain actions, and it may possess a variety of information in order to reason about its and other agent's actions. Thus, our KAROframework tries to de ..."
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Cited by 11 (1 self)
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We present a formal system to reason about and specify the behavior of multiple intelligent artificial agents. Essentially, each agent can perform certain actions, and it may possess a variety of information in order to reason about its and other agent's actions. Thus, our KAROframework tries to deal formally with the notion of Knowledge, possessed by the agents, and their possible execution of actions. In particular, each agent may reason about its or, alternatively, other's Abilities to perform certain actions, the possible Results of such an execution and the availability of the Opportunities to take a particular action. Formally, we combine dynamic and epistemic logic into one modal system, and add the notion of ability to it. We demonstrate that there are several options to define the ability to perform a sequentially composed action, and we outline several properties under two alternative choices. Also, the agents' views on the correctness and feasibility of their plans a...
Modal Model Theory
 ANNALS OF PURE AND APPLIED LOGIC
, 1995
"... This paper contributes to the model theory of modal logic using bisimulations as the fundamental tool. A uniform presentation is given of modal analogues of wellknown definability and preservation results from firstorder logic. These results include algebraic characterizations of modal equivalen ..."
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Cited by 9 (5 self)
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This paper contributes to the model theory of modal logic using bisimulations as the fundamental tool. A uniform presentation is given of modal analogues of wellknown definability and preservation results from firstorder logic. These results include algebraic characterizations of modal equivalence, and of the modally definable classes of models; the preservation results concern preservation of modal formulas under submodels, unions of chains, and homomorphisms.
Using Conceptual Graphs in a Multifaceted Logical Model for Information Retrieval
 In Proceedings of DEXA’96, 7th International Conference on Database and Expert Systems Applications (Zürich, Switzerland). Lecture Notes in Computer Science
, 1996
"... . In 1986, van Rijsbergen promotes a principle in which the matching between a query and a document is founded on a form of uncertain logical inference. His formulation was deliberately abstract, no attempt was made to specify how such a principle might be implemented through an effective logic a ..."
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Cited by 6 (0 self)
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. In 1986, van Rijsbergen promotes a principle in which the matching between a query and a document is founded on a form of uncertain logical inference. His formulation was deliberately abstract, no attempt was made to specify how such a principle might be implemented through an effective logic and under a particular semantics. In classical logics inference which is often associated with logical implication is too strict to be useful in the matching process. To overcome this problem, the possible worlds semantics seems to be a good way to formalize the uncertain inferences needed in an information retrieval system. Thus, in 1988 Nie initiated a work which has as its basic assumption the consideration that a document can be associated to a possible world. We think however that a more refined approach must be adopted especially when complex information are considered. It is based on the notion of facet, which allows to consider a document under several points of view, every o...
An Algebraic and Logical Approach to the Approximation of Regions (Extended Abstract)
"... To be presented at the 5th Seminar on Relational Methods in Computer Science Ivo Dntsch School of Information and Software Engineering University of Ulster at Jordanstown Newtownabbey, BT 37 0QB, N.Ireland I.Duentsch@ulst.ac.uk Ewa Orl/owska Institute of Telecommunications Szachowa 1 04894, Wa ..."
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Cited by 5 (3 self)
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To be presented at the 5th Seminar on Relational Methods in Computer Science Ivo Dntsch School of Information and Software Engineering University of Ulster at Jordanstown Newtownabbey, BT 37 0QB, N.Ireland I.Duentsch@ulst.ac.uk Ewa Orl/owska Institute of Telecommunications Szachowa 1 04894, Warszawa, Poland orlowska@itl.waw.pl Hui Wang School of Information and Software Engineering University of Ulster at Jordanstown Newtownabbey, BT 37 0QB, N.Ireland H.Wang@ulst.ac.uk Abstract We report the definition of a class of algebras which can serve as an algebraic tool for handling regions that can only be approximated due to inappropriate granularity. We also generalise the concepts of "contact relation" and "part of" to the case of incompletely known regions to arrive at approximate contact algebras. Finally, we present a relational proof system for these structures. Proofs and details will be published elsewhere. 1 Introduction It is rarely the case that spatial regions can be d...
A Lindström theorem for modal logic
 Modal Logic and Process Algebra
, 1995
"... A modal analogue of Lindstrom's characterization of firstorder logic is proved. Basic modal logics are characterized as the only modal logics that have a notion of finite rank, or, equivalently, as the strongest modal logic whose formulas are preserved under ultraproducts over !. Also, basic mo ..."
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Cited by 5 (2 self)
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A modal analogue of Lindstrom's characterization of firstorder logic is proved. Basic modal logics are characterized as the only modal logics that have a notion of finite rank, or, equivalently, as the strongest modal logic whose formulas are preserved under ultraproducts over !. Also, basic modal logic is the strongest classical logic whose formulas are preserved under bisimulations and ultraproducts over !.
The Flow of Information in Information Retrieval: Towards a general framework for the modelling of information retrieval
, 1998
"... The flow of information characterizes the notion of information containment and can generally be defined as the information an object contains about another. The purpose of an information retrieval system is to seek document objects that contain information about a query object. Determining thes ..."
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Cited by 4 (1 self)
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The flow of information characterizes the notion of information containment and can generally be defined as the information an object contains about another. The purpose of an information retrieval system is to seek document objects that contain information about a query object. Determining these document objects consists of computing the information contained in them about the query object. Therefore, a modelling approach for information retrieval could be based on a theory that provides for the formal capturing of information and its flow. The modelling approach considered in this paper is based on channel theory, a theory of information that satisfies properties attributed to information and its flow. This paper demonstrates the connection between channel theory and information retrieval. It indicates that channel theory provides an expressive framework for the modelling of information retrieval. In addition, the framework can encompass various features that are becomin...