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SW Portal Internal Research Seminar 04/12/2003. Ontologies: Dynamic Networks of Formally Represented Meaning. Dieter Fensel: Ontologies: Dynamic Networks of Formally Represented Meaning , 2001. SW Portal Internal Research Seminar 04/12/2003.

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Ontologies dynamic networks of formally represented meaning

SW Portal Internal Research Seminar 04/12/2003

Ontologies: Dynamic Networks of Formally Represented Meaning

Dieter Fensel: Ontologies: Dynamic Networks of Formally Represented Meaning, 2001


SW Portal Internal Research Seminar 04/12/2003

Introduction - Ontologies: Formal and Real, based on Consensus

  • Motivation: lack of technology that supports access to unstructured, heterogeneous and distributed information and knowledge sources

  • Goal: to examine some of the essential requirements for such a technology

  • WWW – problems:

    • find, access, present and maintain the information (HTML,SGML,etc.)

    • information content – natural language => gap between the information available for tools and the information kept in a form legible to humans

    • computers – devices that post and render information, but no access to the actual content => offer only limited support => hard for humans not only accessing and processing information, but also extracting and interpreting it


SW Portal Internal Research Seminar 04/12/2003

Introduction - Ontologies: Formal and Real, based on Consensus

  • Sematic Web: provides automated information access based on machine processable

  • semantics of data and heuristics that use these meta data.

    • the explicit representation of the semantics data + domain theories => a Web that provides a qualitatively new level of service

  • Ontologies: key enabeling technology for the semantic web.

    • - need to interweave human understanding of symbols with their machine processability – a closer look to the nature of Ontologies and to the question wheather and how they can actually provide such an service

    • - developed in AI for knowledge sharing and re-use

    • very popular, because of what they promis: a shared and common understanding of a domain that can be communicated between people and application systems.

    • glue together 2 essential aspects:

    • They define formal semantics for information, allowing information processing by a computer.

    • They define real-world semantics, which makes it possible to link machine processable content with meaning for humans based on consensual terminologies.


SW Portal Internal Research Seminar 04/12/2003

Ontologies – formal semantics

  • enables machine processing of the semantics of information

  • formal semantics can be achieved by a layered language architecture

  • The onion model to control complexity


SW Portal Internal Research Seminar 04/12/2003

Ontologies – real-world semantics

  • how can Ontologies be used to communicate real-world semantics between human and artificial agents?

  • difference between viewing ontologies as “true” models of the real world or steps in a process of organizing evolving consensus.

  • ontologies can only be viewed as a network of interwoven ontologies(may have overlapping and excluding pieces, and must be dynamic in nature) => Ontologies as

  • dynamic networks of formally represented meaning

  • ontologies must have a network architecture and Ontologies must be dynamic.

Joined set of symbols and a consensual interpretation

Agent 1

Agent 2

Communication


SW Portal Internal Research Seminar 04/12/2003

Heterogeneity in Space: Ontology as Networks of Meaning (1)

  • an island of meaning must be interwoven to form more complex structures enabling exchange of information beyond domain, task, and sociological boundaries.

  • tool support must be provided to define local domain models that express a commitment of a group of agents that share a certain domain and task and that can agree on a joined world view for this purpose.

  • links must be defined between these Ontologies and this network must allow overlapping Ontologies with conflicting, and even contradictory - conceptualizations.

  • heterogeneity has been an essential requirement for this Ontology network.

  • ex: Gnutella (a P2P network) – agents were able to enter and leave the network dynamically; they could also communicate with a local environment of other agents.


SW Portal Internal Research Seminar 04/12/2003

Heterogeneity in Space: Ontology as Networks of Meaning (2)

  • What is needed is focus on:

  • • linking local conceptualizations that deal with heterogen definitions and personalized views.

  • • support in easy configuration and re-configuration of such networks according to the communication needs of agent coalitions.

  • • methods and tools that help agents to organize consensus, allowing them to exchange meaning.


SW Portal Internal Research Seminar 04/12/2003

Development in time: Living Ontologies

  • ontologies as pre-requisite for consensus

  • • ontologies as a result of consensus

  • an ontology is as much required for the exchange of meaning as the exchange of meaning may influence and modify an ontology => evolving ontologies describe a process rather than a static model.

  • the real challenge: protocols for the process of evolving ontologie.

  • evolving over time - an essential requirement for useful ontologies.

ontologies cannot be understood as a static model


SW Portal Internal Research Seminar 04/12/2003

Conclusions

  • ontologies help to establish consensual terminologies that make sense to both sites.

  • • computers are able to process information based on their machine-processable semantics; humans are able to make sense of this information based on their connection to real-world semantics.

  • • a model or “protocol” for driving the network that maintains the process of evolving ontologies is the real challenge for making the semantic web reality.

  • Ontologies as Networks of Meaning and Living Ontologies


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