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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


Ontologies dynamic networks of formally represented meaning

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


Ontologies dynamic networks of formally represented meaning

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.


Ontologies dynamic networks of formally represented meaning

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


Ontologies dynamic networks of formally represented meaning

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


Ontologies dynamic networks of formally represented meaning

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.


Ontologies dynamic networks of formally represented meaning

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.


Ontologies dynamic networks of formally represented 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


Ontologies dynamic networks of formally represented meaning

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