Documenting Classes and Properties

• consider http://www.w3.org/2000/10/swap/test/demo1/biology#Dog
  • Would a wolf qualify as a one of these?
  • How about a Dingo?
• publish a document which declares your intended meaning
• allows software to...
  • present data better to a user
  • make conclusions using related terms
  • check for some kinds of errors
  • dynamically update to use and recognize new URIs

Standard Terms: RDFS and OWL

• RDF Vocabulary Description Language 1.0: RDF Schema: rdfs:subClassOf, rdfs:label, ...
• OWL Web Ontology Language: owl:FunctionalProperty etc.
• OWL Guide Appendix lists all 50

Informal Documentation

• rdfs:comment -- unstructured documentation
• rdfs:label human-readable name
• rdfs:seeAlso -- untyped links.

:CanisFamiliaris 
  rdfs:comment """The class of animals designated 
               Canis familiaris (domestic dog).  This
               includes all the dog breeds, but
               not wolves.""";
  rdfs:label "Canis familiaris";
  rdfs:seeAlso <http://www.agrobiologicals.com/glossary/G3089.htm>.

rdfs:comment

A paragraph or two.

• Allow a developer thinking of using the term to decide whether it is what they want.
• Allow a user filling in a form to get hover-over help as to what a field means.
• Remind yourself later what you were thinking about ;-)

rdfs:label

• Don't capitalize - UI software can do that
• Do add labels in many languages for widely used ontologies

For properties:

• For user interfaces as a form field name
• Arrow labels in circles-and-arrow diagrams
• Use a 'role noun' noun
  • E.g. 'author' not 'wrote'
  • E.g. 'parent' not 'has parent' or 'is child of'

For classes:

• Use a singular noun
  • E.g. 'person' not 'people'

Synonyms

• two URIs mean the same thing:

  :Pat owl:sameAs :Patrick.

• everything true of :Pat was also true of :Patrick and everything true of :Patrick was true of :Pat.
• This is what N3 means with "="
• You can add these later to connect to other ontologies

See @@'s work connecting existing ontologies

Class equivalence

• same class membership:

  :Dog owl:equivalentClass :CanisFamiliaris.

• identical thing; membership as well as rdfs:label and other properties:

  :Dog owl:sameAs :CanisFamiliaris.

Many-to-one

• many to one: owl:FunctionalProperty; e.g.

  :mother a owl:FunctionalProperty.

• used to infer sameness:
  • if...

    :sam :mother :jackie.
    :sam :mother :jacqueline.

  • ... then

    :jackie = :jacqueline.

One-to-many

• if...

  contact:mailbox a owl:InverseFunctionalProperty.
  :jacqueline contact:mailbox <mailto:j@example.org>.
  :jackie contact:mailbox <mailto:j@example.org>.

• ... then

  :jackie = :jacqueline.

Different and Disjoint

• maybe :jackie and :jacqueline are different people; what we said about :sam was a mistake
• we can say they're different:

  :jackie owl:differentFrom :jacqueline.

• OWL consistency checkers can find this inconsistency

Class Hierarchies

:Man s:subclassOf :Human .
:YoungMan s:subclassOf :Man .

:CanisFamiliarisDingo 
  owl:subClassOf :CanisFamiliaris;   # Dingos are Dogs!
  rdfs:seeAlso
   <http://www.naturalworlds.org/wolf/canis/Canis_familiaris_dingo.htm>.

:CanisRufus a owl:Class;
  owl:subClassOf :Canis;
  owl:disjointFrom :CanisFamiliaris;     # Wolves are not Dogs!
  rdfs:label "Red Wolf";
  rdfs:comment """As of 1999 there were about 300 individuals 
               of this endangered species""";
  rdfs:seeAlso <http://druidry.org/obod/endangered/redwolf.html>.

Saying that classes are disjoint can help OWL systems detect input errors and data errors as well as ontology errors.

Domain, Range

:father s:domain :Human; s:range :Man.
:Sara :father :Alan.
______________________________________
:Sara a :Human.  :Alan a :Man.

If the ontology gives the domain and range of properties, then the data doesn't have to give the class of everything.

More Information

• This presentation : http://dig.csail.mit.edu/2007/Talks/0108-vocab-tbl/

This work is licensed under a Creative Commons Attribution - Non-Commercial - No Derivatives 2.5 License.