Logical Formalisms for Agreement Technologies
This chapter provides an overview of the logical formalisms that have been proposed to define the formal semantics of knowledge systems that are distributed, heterogeneous and multi contextual. It starts with the abstract notions that are common to many o
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Logical Formalisms for Agreement Technologies Antoine Zimmermann
5.1 Introduction Semantic Web standards offer a good basis for representing the knowledge of local agents,1 the schemata, the functionalities and all things that matter in order to achieve a goal in agreement with other agents. However, the formalisms behind these technologies have limitations when dealing with the distributed, open and heterogeneous nature of the systems concerned by Agreement Technologies. In particular, since agents are inherently autonomous, they define their knowledge according to their own beliefs, which can differ from one another or even be inconsistent with other agents’ beliefs. Since the standards of the Semantic Web are not concerned about belief and they do not provide the means to compartment knowledge from distinct sources, the conclusions reached when using the global knowledge of disagreeing agents are inevitably inconsistent. Hence, by virtue of the “principle of explosion”, all possible statements are entailed. For these reasons, a number of logical formalisms have been proposed to handle the situations in which pieces of knowledge are defined independently in various contexts. These formalisms extend classical logics—sometimes the logics of Semantic Web standards—by partitioning knowledge from different sources and limiting the interactions between the parts in the partition in various ways. We collectively call these logics contextual logics, although they have been called sometimes distributed logics (Borgida and Serafini 2003; Ghidini and Serafini 2000; Homola 2007) or modular ontology languages (Cuenca-Grau and Kutz 2007).
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use the term “agent” to denote any entity which can act towards a goal, such as a service, an application, a device, or even a person or organisation. A. Zimmermann () École Nationale Supérieure des Mines, FAYOL-ENSMSE, LSTI, F-42023 Saint-Étienne, France e-mail: [email protected] S. Ossowski (ed.), Agreement Technologies, Law, Governance and Technology Series 8, DOI 10.1007/978-94-007-5583-3__5, © Springer Science+Business Media Dordrecht 2013
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A. Zimmermann
This chapter aims at presenting a variety of proposals for contextual reasoning, where each approach addresses to a certain extent the problems of heterogeneity, inconsistency, contextuality and modularity.
5.2 General Definitions for Contextual Logics 5.2.1 Networks of Aligned Ontologies In most of the formalisms presented here, it is generally agreed that local knowledge, defined to serve one purpose from one viewpoint, should conform to a classical semantics, that is, the semantics of standard knowledge representation formats. For instance, the ontology that defines the terms used in the dataset of a single semantic website could be defined in OWL and all the conclusions that can be drawn from it are determined according to the W3C specification. Similarly, the functionalities of a single Web service could be described in WSML, and using this description alone would yield the inferences defined by the WSML
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