1. Ontologies for Cadastral Processes Gerhard Navratil COST G9-Meeting Aalborg, 25.-26.8.2005

2. Gerhard Navratil Overview Intention Ontologies Why use ontologies? Hess/Vaskovich-ontology Critical points My personal problems Improvement (?) Conclusions

3. Gerhard Navratil Intention Erik Stubkjaer in Thessaloniki: Please take a look at the Ontology and tell us what you think … Ontology: Tool to understand structures Intention of the presentation: –Showing problems I had –Suggestions to improve the ontology

4. Gerhard Navratil Ontology Elements (Horrige et al. ‚A practical guide to Building OWL Ontologies‘) Ontologies are used to capture knowledge about some domains of interest. –Individuals: Objects (we are interested in) –Properties: Binary relations –Classes: Sets of individuals with unique behavior

5. Gerhard Navratil Why Ontologies? Ontologies allow representation of knowledge in a formal way Check internal consistency of the model Comparison of systems with reasoners Ontologies with computing possibilities: Make experiments, test hypothesis

6. Gerhard Navratil Hess/Vaskovich-Ontology (1) Based on process descriptions (activity diagrams) by Marina Vaskovich Ontology describes one process: –Classes: Activity, Function, Result –Properties:Activity has a function Activity has a result –Individuals: Different activities, functions, results

7. Gerhard Navratil Hess/Vaskovich-Ontology (2)

8. Gerhard Navratil Top-Level Ontology Contains concepts used in the cadastral models Activity Actor/(Organizational) Role Document Function Pre- and Post-Conditions Deadline

9. Gerhard Navratil Critical points Concepts in the top level ontology –Cadastral philosophy (title vs. deed) Creating the ontology: (Kuhn, 2000) –Knowledge engineers use their understanding to model the domain – gathered from interviews, documents, databases, etc. –Domain experts have to verify the abstract models Proposal by Kuhn: Ontologies based on natural language (text)

10. Gerhard Navratil My Personal Problems Sequence of steps: Getting an overview Testing the correctness of the model: Correspondence with reality

11. Gerhard Navratil Improvements (?) Results can be different Knowledge or proof is different than an unsigned document – Separate? Involved persons are not represented yet – a process has actor(s) as properties Will the reasoner still produce results? Ordering of steps – concept of time Make it running – test it with examples Would it be simpler to understand the process if we ignore the mortgage in a first step?

12. Gerhard Navratil Conclusions Model proved that the step from the activity diagrams to the OWL ontology is possible Limited comparison is possible Future work should include time, persons We need a simple method to check the correctness of the model