Lab: OWL 2

Topics

• Basic OWL ontology editing in Protégé.
• WebVOWL visualisation.

Useful materials

Readings:

• Protégé 5 Documentation
  • Installation
  • Getting Started
  • An online version, Webprotégé, is also available, but we recommend that you download the Desktop version and run it locally.
• Youtube Playlist with quick tutorials of Protégé, particularly video 1 - 5
• OWL Documentation (from S09)
• Lab presentation of Protégé

Vocabularies and terms (from S10) - this is for reference: you will not need them all :-):

• Friend of a Friend (FOAF) (if necessary follow the link to the 2004 version)
• Event Ontology (event)
• Time ontology in OWL (time, OWL-time)
• geo: World Geodetic Standard (WGS) 84
• Dublin Core (DC)
• SKOS - Simple Knowledge Organization System Home Page
• Semantic Interlinked Online Communities (SIOC)

Tasks

Task. Follow the Protégé 5 Installation instructions to download and install Protégé Desktop.

Task. Go through the Protégé 5 Getting Started advice to learn the basics of Protégé Desktop.

Task. Create a new InvestigationOntology that can be used to represent the Mueller Investigation, as well as other public investigations. Choose a prefix (for example io:) path for the ontology, and save the empty ontology to a file.

Task. Start adding classes and properties to your ontology. Use the experience from earlier exercises. For example, the ontology can include these top-level classes:

• Investigation
• Person

Subclasses of Person can be

• Investigator
• InvestigatedPerson

A subclass of Investigator can be InvestigationLeader.

Task. Connect your classes to at least one class from a well-known ontology, for example foaf:Person. There are three ways you can do this do this:

1. use foaf:Person instead of "your own" Person class;
2. make "your own" Person class an rdfs:subClassOf foaf:Person; or
3. make "your own" Person class owl:equivalentClass to foaf:Person.

Alternative 2 is most common but all are ok.

Hint 1: You must first create foaf:Person as a class in your ontology. Hint 2: Use the Ontology Prefixes sub-tab in the Active ontology tab to define a new prefix.

Task. Create or reuse data properties for

• investigation title and description;
• person names; and
• investigation start and end times.

Hint: To reuse a property from another vocabulary, you need to create it as a property in your ontology.

Task, Define the proper domains and ranges of your data properties. Should some of them be marked as Functional?

Task. Along the way, keep saving the ontology to a file, and use WebVOWL to visualise it (either Run WebVOWL or Old WebVOWL version). Keep improving the ontology until it looks the way you think it should.

Task. Also along the way, go to the Reasoner menu and choose the HermiT reasoner. Use Reasoner -> Start reasoner to check that your ontology is consistent.

Tip: When you change the ontology and the reasoner is running, you must use Reasoner -> Synchronize to reason over the changes.

Task.

• Create or import object properties for stating that a person is involved in an investigation.
• Create subproperties of involved in for stating that a person can be indicted in, investigating, or leading an investigation.

Task. Define the proper domains and ranges of your object properties. Should some of them have particular Characteristics?

If you have more time

Task. Stop the reasoner, and add individuals to represent that:

• Robert Mueller lead the Mueller Investigation.
• Paul Manafort was indicted.
• Elizabeth Prelogar was an investigator.

Task. Start the reasoner again. Have any axioms/triples been added to the ontology?

Task. Can you do a change that makes your ontology inconsistent? (Save often, so you always have a consistent version to revert to :-))

Task. You can add a lot more classes (types) and relations (object properties) to your ontology. For example:

• InvestigationTeam, which has all the Investigators as members