- Email: [email protected]
Reasoning with Context in the Semantic Web
Web Semantics: Science, Services and Agents on the World Wide Web 12–13 (2012) 1–2
Contents lists available at SciVerse ScienceDirect
Web Semantics: Science, Services and Agents on the World Wide Web journal homepage: http://www.elsevier.com/locate/websem
Editorial
Reasoning with Context in the Semantic Web
This Special Issue on Reasoning with Context in the Semantic Web collects ten articles that shed direct or indirect light on the role of context in Semantic Web theories and applications. Context has become a key-factor for the realization of the Semantic Web. There is a growing need for general and robust modeling and reasoning techniques that make it possible to handle the heterogeneity of knowledge, for instance, in situations where the same term has different meanings in different domains. Also the homogeneity of knowledge requires a context-based treatment, for instance, in situations where different terms have the same meaning in different domains, or where they may be seen as representing a coherent sub-domain. Research on these topics has mostly concentrated on the relationship between formal ontologies, which are the logical structures that encode the semantics of a software’s domain of application, and their context of use, or of development and maintenance, or of communication. This has resulted in three main research areas. Research on the Semantic Web, as well as on: information integration, distributed knowledge management, multi-agent and distributed reasoning, has often aimed at clarifying issues related to context of use. One of the main research questions here is how to relate knowledge that is distributed over many resources. Recent developments suggest that aspects of this relation can be captured by means of named graphs (to express meta-information), the use of provenance (to track the context where data/axioms came from) and querying (to facilitate reasoning). On the other hand, research on ontology engineering and maintenance has tackled the problems faced by ontology engineers when developing and maintaining an ontology. The automation of the process of ontology development and of its phases (knowledge elicitation, revision cycles, alignment with pre-existing ontologies) has improved efficiency, reduced the introduction of unintended meanings into ontologies and made explicit the relationship between an ontology and its development and maintenance context. Finally, research on problem solving and agent communication has explored how an agent’s ontology needs to change at run-time because of interactions with its context – for instance with other agents whose ontologies are not known or with new world situations. This type of research has delivered a deeper understanding of the evolution of an ontology with respect to its context. Although all ten articles present results that clarify various aspects of the relationship between ontologies and their context, they can be grouped according to the three research areas described above. A first group of five articles investigates the relationship between formal ontologies and their context of use. 1570-8268/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.websem.2011.12.004
In ‘‘Representing and Querying Validity Time in RDF and OWL: A Logic-Based Approach’’ Motik focuses on validity time, defined as the time instants at which a given statement is true. The author proposes an extension of SPARQL with primitives that allow for querying temporal graphs. Here context is understood as the statements that are relevant to answering a given query and that are true at the same instant in time. In ‘‘Context-Dependent Views to Axioms and Consequences of Semantic Web Ontologies’’ Baader, Knechtel and Peñaloza investigate how pre-computation in Description Logics can be employed to yield fast access to implicit knowledge. The authors focus on situations where users operate in contexts which allow to access only parts of an ontology and should therefore see only what follows from these parts. In their approach contexts are modeled by labels, and efficiency is achieved by pre-computing only boundaries for consequences. In this proposal context is understood as level (such as level of expertise of the user, or as a user’s access rights, or as level of detail). In ‘‘Towards a context sensitive approach to searching information based on domain specific knowledge sources’’ Dinh and Tamine combine contextual semantic information in documents and user queries to improve the performance of biomedical information retrieval through document expansion and query expansion. The authors adopt the long-standing distinction between global context, which is understood here as domain knowledge sources, and local context, understood here as statistically ranked documents. In ‘‘Domains and context: first steps towards managing diversity in knowledge’’ Giunchiglia, Maltese and Dutta propose to tackle the problem of scaling up semantic matching techniques by using curated background knowledge. This, they argue, accounts for knowledge diversity and allows to make explicit local semantics. In their proposal the notion of context is based on the first author’s previous work, where it was defined as ‘‘a tool to specifically localize reasoning to a subset of facts known by an agent’’. In ‘‘Contextualized Knowledge Repositories for the Semantic Web’’ Serafini and Homola propose to adapt theories of context for application in the Semantic Web. The presented notion of Contextualized Knowledge Repository is composed of a set of OWL 2 knowledge bases, which are embedded in a context by a set of qualifying attributes (such as time, space, topic) specifying the boundaries within which the knowledge base is assumed to be true. Here, again, contexts are modeled as labels and organized by a hierarchical coverage relation. A second group of three articles concentrates on the relationship between formal ontologies and their context of development and maintenance.
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Editorial / Web Semantics: Science, Services and Agents on the World Wide Web 12–13 (2012) 1–2
In ‘‘Interactive Ontology debugging: two query strategies for efficient fault localization’’ Shchekotykhin, Friedrich, Fleiss and Rodler present an approach to diagnosing faulty ontologies by acquiring information through sequences of queries answered by some oracle, such as a user or an information extraction system. Although their article does not provide a direct treatment of context, such notion is closely related to what they call local model, which encodes one’s view on a domain. In ‘‘Higher-Order Aspects and Context in SUMO’’ Benzmüller and Pease address the automation of higher-order aspects in expressive ontologies, providing evidence that higher-order automated theorem provers can be employed for modeling temporal, epistemic, or doxastic contexts. The case study is the modeling of contexts as embedded formulas (formulas as terms) in the Suggested Upper Merged Ontology (SUMO). In ‘‘Interactive Ontology Revision’’ Nikitina, Rudolph and Glimm present an approach to efficient reasoning-supported interactive ontology revision, with a focus on quality assurance of automatically acquired knowledge. Here context plays a role because quality assurance should take into account the original context of the acquired knowledge in order to decide how much of such knowledge can be used in the new, target context. The final group of articles concentrates on the relationship between formal ontologies and their context of communication. In ‘‘An Interaction-Based Approach to Semantic Alignment’’ Atencia and Schorlemmer propose to deal with semantic heterogeneity in agent communication by means of an interaction-based approach to semantic alignment inspired by category theory. Here context is interaction, specified in terms of regulatory communication protocols. Finally, in ‘‘OWL-POLAR: A Framework for Semantic Policy Representation and Reasoning’’ Sensoy, Norman, Vasconcelos and Sycara present an OWL-based language to express types of policies which enables both policy-governed decision-making and policy analysis within the bounds of decidability. Although also this article does not provide a direct treatment of the notion of context, here contexts are approximated by or depend on policies: system-level principles of ideal activity. This collection of articles provides a valuable overview as well as insight into mature approaches to issues involving the use of
context in the Semantic Web. The special issue could not have come together without the invaluable contribution of the reviewers listed below, some of whom volunteered from the ranks of the Journal’s Editorial Board while others had previously served as PC members of the workshop series on Automated Reasoning about Context and Ontology Evolution (ARCOE): Franz Baader, Christoph Benzmüller, Katarina Britz, Jérôme Euzenat, Nicola Fanizzi, Giorgos Flouris, Aurona Gerber, Chiara Ghidini, Claudio Gutierrez, Frank van Harmelen, Hong-Gee Kim, Manolis Koubarakis, Thomas Meyer, Alessandra Mileo, Amedeo Napoli, Maurice Pagnucco, Valeria de Paiva, Dimitris Plexousakis, Guilin Qi, Márcio Ribeiro, François Scharffe, Thomas Schneider, Cassia Trojahn dos Santos, Renata Wassermann, Takahira Yamaguchi. Jos Lehmann School of Informatics, University of Edinburgh, Informatics Forum, 10 Crichton Street, Edinburgh EH8 9AB, UK E-mail addresses: [email protected], [email protected], [email protected] Ivan José Varzinczak CSIR Meraka Institute, Meiring Naude Road, 0001 Pretoria, South Africa School of Computer Science, University of KwaZulu-Natal, Durban, South Africa E-mail address: [email protected] Alan Bundy School of Informatics, University of Edinburgh, Informatics Forum, 10 Crichton Street, Edinburgh EH8 9AB, UK E-mail address: [email protected] Available online 23 December 2011
Contents lists available at SciVerse ScienceDirect
Web Semantics: Science, Services and Agents on the World Wide Web journal homepage: http://www.elsevier.com/locate/websem
Editorial
Reasoning with Context in the Semantic Web
This Special Issue on Reasoning with Context in the Semantic Web collects ten articles that shed direct or indirect light on the role of context in Semantic Web theories and applications. Context has become a key-factor for the realization of the Semantic Web. There is a growing need for general and robust modeling and reasoning techniques that make it possible to handle the heterogeneity of knowledge, for instance, in situations where the same term has different meanings in different domains. Also the homogeneity of knowledge requires a context-based treatment, for instance, in situations where different terms have the same meaning in different domains, or where they may be seen as representing a coherent sub-domain. Research on these topics has mostly concentrated on the relationship between formal ontologies, which are the logical structures that encode the semantics of a software’s domain of application, and their context of use, or of development and maintenance, or of communication. This has resulted in three main research areas. Research on the Semantic Web, as well as on: information integration, distributed knowledge management, multi-agent and distributed reasoning, has often aimed at clarifying issues related to context of use. One of the main research questions here is how to relate knowledge that is distributed over many resources. Recent developments suggest that aspects of this relation can be captured by means of named graphs (to express meta-information), the use of provenance (to track the context where data/axioms came from) and querying (to facilitate reasoning). On the other hand, research on ontology engineering and maintenance has tackled the problems faced by ontology engineers when developing and maintaining an ontology. The automation of the process of ontology development and of its phases (knowledge elicitation, revision cycles, alignment with pre-existing ontologies) has improved efficiency, reduced the introduction of unintended meanings into ontologies and made explicit the relationship between an ontology and its development and maintenance context. Finally, research on problem solving and agent communication has explored how an agent’s ontology needs to change at run-time because of interactions with its context – for instance with other agents whose ontologies are not known or with new world situations. This type of research has delivered a deeper understanding of the evolution of an ontology with respect to its context. Although all ten articles present results that clarify various aspects of the relationship between ontologies and their context, they can be grouped according to the three research areas described above. A first group of five articles investigates the relationship between formal ontologies and their context of use. 1570-8268/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.websem.2011.12.004
In ‘‘Representing and Querying Validity Time in RDF and OWL: A Logic-Based Approach’’ Motik focuses on validity time, defined as the time instants at which a given statement is true. The author proposes an extension of SPARQL with primitives that allow for querying temporal graphs. Here context is understood as the statements that are relevant to answering a given query and that are true at the same instant in time. In ‘‘Context-Dependent Views to Axioms and Consequences of Semantic Web Ontologies’’ Baader, Knechtel and Peñaloza investigate how pre-computation in Description Logics can be employed to yield fast access to implicit knowledge. The authors focus on situations where users operate in contexts which allow to access only parts of an ontology and should therefore see only what follows from these parts. In their approach contexts are modeled by labels, and efficiency is achieved by pre-computing only boundaries for consequences. In this proposal context is understood as level (such as level of expertise of the user, or as a user’s access rights, or as level of detail). In ‘‘Towards a context sensitive approach to searching information based on domain specific knowledge sources’’ Dinh and Tamine combine contextual semantic information in documents and user queries to improve the performance of biomedical information retrieval through document expansion and query expansion. The authors adopt the long-standing distinction between global context, which is understood here as domain knowledge sources, and local context, understood here as statistically ranked documents. In ‘‘Domains and context: first steps towards managing diversity in knowledge’’ Giunchiglia, Maltese and Dutta propose to tackle the problem of scaling up semantic matching techniques by using curated background knowledge. This, they argue, accounts for knowledge diversity and allows to make explicit local semantics. In their proposal the notion of context is based on the first author’s previous work, where it was defined as ‘‘a tool to specifically localize reasoning to a subset of facts known by an agent’’. In ‘‘Contextualized Knowledge Repositories for the Semantic Web’’ Serafini and Homola propose to adapt theories of context for application in the Semantic Web. The presented notion of Contextualized Knowledge Repository is composed of a set of OWL 2 knowledge bases, which are embedded in a context by a set of qualifying attributes (such as time, space, topic) specifying the boundaries within which the knowledge base is assumed to be true. Here, again, contexts are modeled as labels and organized by a hierarchical coverage relation. A second group of three articles concentrates on the relationship between formal ontologies and their context of development and maintenance.
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Editorial / Web Semantics: Science, Services and Agents on the World Wide Web 12–13 (2012) 1–2
In ‘‘Interactive Ontology debugging: two query strategies for efficient fault localization’’ Shchekotykhin, Friedrich, Fleiss and Rodler present an approach to diagnosing faulty ontologies by acquiring information through sequences of queries answered by some oracle, such as a user or an information extraction system. Although their article does not provide a direct treatment of context, such notion is closely related to what they call local model, which encodes one’s view on a domain. In ‘‘Higher-Order Aspects and Context in SUMO’’ Benzmüller and Pease address the automation of higher-order aspects in expressive ontologies, providing evidence that higher-order automated theorem provers can be employed for modeling temporal, epistemic, or doxastic contexts. The case study is the modeling of contexts as embedded formulas (formulas as terms) in the Suggested Upper Merged Ontology (SUMO). In ‘‘Interactive Ontology Revision’’ Nikitina, Rudolph and Glimm present an approach to efficient reasoning-supported interactive ontology revision, with a focus on quality assurance of automatically acquired knowledge. Here context plays a role because quality assurance should take into account the original context of the acquired knowledge in order to decide how much of such knowledge can be used in the new, target context. The final group of articles concentrates on the relationship between formal ontologies and their context of communication. In ‘‘An Interaction-Based Approach to Semantic Alignment’’ Atencia and Schorlemmer propose to deal with semantic heterogeneity in agent communication by means of an interaction-based approach to semantic alignment inspired by category theory. Here context is interaction, specified in terms of regulatory communication protocols. Finally, in ‘‘OWL-POLAR: A Framework for Semantic Policy Representation and Reasoning’’ Sensoy, Norman, Vasconcelos and Sycara present an OWL-based language to express types of policies which enables both policy-governed decision-making and policy analysis within the bounds of decidability. Although also this article does not provide a direct treatment of the notion of context, here contexts are approximated by or depend on policies: system-level principles of ideal activity. This collection of articles provides a valuable overview as well as insight into mature approaches to issues involving the use of
context in the Semantic Web. The special issue could not have come together without the invaluable contribution of the reviewers listed below, some of whom volunteered from the ranks of the Journal’s Editorial Board while others had previously served as PC members of the workshop series on Automated Reasoning about Context and Ontology Evolution (ARCOE): Franz Baader, Christoph Benzmüller, Katarina Britz, Jérôme Euzenat, Nicola Fanizzi, Giorgos Flouris, Aurona Gerber, Chiara Ghidini, Claudio Gutierrez, Frank van Harmelen, Hong-Gee Kim, Manolis Koubarakis, Thomas Meyer, Alessandra Mileo, Amedeo Napoli, Maurice Pagnucco, Valeria de Paiva, Dimitris Plexousakis, Guilin Qi, Márcio Ribeiro, François Scharffe, Thomas Schneider, Cassia Trojahn dos Santos, Renata Wassermann, Takahira Yamaguchi. Jos Lehmann School of Informatics, University of Edinburgh, Informatics Forum, 10 Crichton Street, Edinburgh EH8 9AB, UK E-mail addresses: [email protected], [email protected], [email protected] Ivan José Varzinczak CSIR Meraka Institute, Meiring Naude Road, 0001 Pretoria, South Africa School of Computer Science, University of KwaZulu-Natal, Durban, South Africa E-mail address: [email protected] Alan Bundy School of Informatics, University of Edinburgh, Informatics Forum, 10 Crichton Street, Edinburgh EH8 9AB, UK E-mail address: [email protected] Available online 23 December 2011