Ontology Engineering Lab #5 – September 30, 2013

Review for Quiz  Versioning Ontologies  prohibited combinations of Ontology IRIs and Version IRIs  uniqueness constraints  RDF  Triple format  Graph representation  Syntax rules – e.g. subject cannot be a literal

Review for Quiz  RDF, RDFS and OWL  Translation into natural language  Example:  OE_002 rdf:type owl:Class  translates to: OE_002 is a Class  Example:  OE_002 rdf:type owl:Class  OE_101 rdf:type OE_002  OE_102 rdf:type OE_002  OE_004 rdf:type owl:Property  OE_101 OE_004 OE_102  Translates to: OE_101 and OE_102 are instances of class OE_002 and OE_101 is related to OE_102 by the property OE_004

Review for Quiz  RDF, RDFS and OWL  Translation from natural language  Example:  Apples are a kind of Fruit  Translates to:  Apple rdf:type owl:Class  Fruit rdf:type owl:Class  Apple rdfs:SubClassOf Fruit  Example:  This apple is green  Translates to:  Apple rdf:type owl:Class  OE_001 rdf:type Apple  Green rdf:type owl:Class  OE_002 rdf:type Green  has_quality rdf:type owl:Property  OE_001 has_quality OE_002

Review for Quiz  Identify and explain problems in taxonomies  Use – Mention error  Is_a overloading (e.g. use of part of relation instead of subclass relation to order the taxonomy  Logic of Terms  Non-Disjoint Classes  Terminology  Primitive vs. Defined Classes  Enumerative Class

Review for Quiz  Class Restrictions – identify kind of restriction  Subclass restrictions as necessary conditions  Equivalent to restrictions as necessary and sufficient conditions  Existential restrictions  Universal restrictions  Cardinality restrictions  Min, Max, Exactly  Example:  Every International traveller has at least one passport  Subclass restriction & Min Cardinality restriction

Review for Quiz  Open and Closed World Assumptions  Explain inference based upon either  Example: Under a Closed World Assumption which of the following statements is implied by the statement that 2 is an even number and that no other information about 2 is available?  2 is not an odd number  2 is not a prime number  2 is divisible by 2  2 is greater than 1  Closure Axioms  Create a closure axiom for the class RDF statement that has three subclass restrictions:  Every RDF Statement has part some Subject  Every RDF Statement has part some Predicate  Every RDF Statement has part some Object  Solution: Every RDF has part only (Subject or Predicate or Object)

Review for Quiz  Coverage Axiom  Example: Create a coverage axiom for the class Widget that has three subclasses: SmallWidget, MediumWidget, and LargeWidget  The class Widget is a subclass of the union of Small, Medium and Large Widget Classes  Inferences based upon the types of Object Properties  Functional, Reflexive, Irreflexive, Symmetric, Asymmetric and Transitive  Example: The property R is an asymmetric and transitive property. What can be inferred from the facts:  x is related by R to y  y is related by R to z

Review for Quiz  Review Session – Saturday 5th 10am – 12pm. Meet by Philosophy Department Office in 1st floor of Park Hall  BFO version 1.1 can be downloaded from In the Implementations section click on the OWL-DL hyperlink