1. Ontology Engineering Lab #2 – September 9, 2013 1

2. Review – Ontology Identifiers and Versioning 2 Ontology 1.0 Ontology IRI Ontology 1.1 Ontology 1.2 Ontology 1.n Version 1.0 IRIVersion 1.1 IRIVersion 1.2 IRIVersion 1.n IRI Current Version accessible by

3. Review – Violations of Versioning Uniqueness Constraints 3 Ontology 1 Ontology IRI: XXXXX Ontology 2 Ontology 1 Ontology IRI: XXXXX Ontology 2 Version IRI: YYYYY

4. Data Definition Languages 4  Computer processable data requires structures that are defined in a manner to which applications can respond as expected  Structured Query Language – contains statements that build database tables CREATE TABLE customers ( customer_id number(10) not null, customer_name varchar2(50) not null, address varchar2(50), city varchar2(50), state varchar2(25), zip_code varchar2(10), CONSTRAINT customers_pk PRIMARY KEY (customer_id) ); * * from http://www.techonthenet.com/sql/tables/create_table.php

5. RDF, RDF-S and OWL  The Resource Description Framework (RDF), Resource Description Framework Schema (RDF-S) and Web Ontology Language (OWL) are a trio of languages that allow us to describe the structure of ontologies  The content of these languages is on the web at these URLs:  RDF: http://www.w3.org/1999/02/22-rdf-syntax-ns#http://www.w3.org/1999/02/22-rdf-syntax-ns#  RDF-S: http://www.w3.org/2000/01/rdf-schema#http://www.w3.org/2000/01/rdf-schema#  OWL: http://www.w3.org/2002/07/owl#http://www.w3.org/2002/07/owl# 5

6. Well Formed Expressions 6  RDF specifies a regular syntax for well formed expressions  rdf:statement – a simple expression that relates one entity to another  rdf:subject – the entity the statement is about  rdf:predicate – the relationship said to hold between the two entities  rdf:object – the entity that is related to the subject  Humans are mortal  UB’s website homepage has URL http://www.buffalo.edu/  Remus is the brother of Romulus

7. RDF Graphs 7 Remus is_brother_of Romulus founder_of Nodes Edges The direction of the edges is always away from the subject and towards the object of the statement Rome

8. A Couple of Rules for RDF Statements 8  Subject and Predicate have to be resources  Object – can be either a resource or a literal  Behind the display in Protégé the statement: Humans are mortal will look like:  And the statement: The URL of UB’s website is http://www.buffalo.edu/ will look like: "http://www.buffalo.edu/"

9. RDF, RDF-S and OWL  owl:Class is used to declare an entity to be a class  rdfs:subClassOf is used to declare that one class is a subclass of another  rdf:type is used to declare that a resource is an instance of a given type  rdf:Property is used to declare that a resource is a relation…  Between a resource and an annotation (annotation property)  Between a resource and a literal value (datatype property)  Between a resource and another resource (object property)  rdfs:subPropertyOf is used to declare that one property is a subproperty of another 9

10. 1st (poor) Attempt at “Ontologizing” the Customer Table 10 Customer Zip CodeState City Address Customer Name Customer ID has ZIP code has ID has name has address has City has State

11. Improved Attempt at Ontologizing 11 Customer Zip CodeState City Address Person Name Customer ID located in agent in has role designates participates in designates Person Act Of Inhabitance Facility Geospatial Region Land Lot designates part ofnear part of

12. Enriching a Taxonomy with Restrictions 12  owl:Restriction used to create an anonymous class (as opposed to a named class) that can be used to describe either necessary or necessary and sufficient conditions for class membership  Existential Restrictions: members have at least one member of the object of the restriction  Example: persons are children of at least one person  Example: orchestras have at least one section of woodwinds  Universal Restrictions: members have only members of the object of the restriction  Example: temporal intervals are composed of only temporal intervals  Example: organizations have subsidiary only organization

13. Enriching a Taxonomy with Restrictions 13  Necessary Restrictions are a means to define subclass relationships  Example: humans are mortal  Example: universities are institutions of higher-education  Example: bicycles are two-wheeled vehicles  Necessary and Sufficient Restrictions are a means to create equivalent class relationships  Example: days are 24 hour periods  Example: bachelors are unmarried males  Example: even numbers are divisible by 2

14. Building a Taxonomy – Common Problems 14  Use – Mention Errors  Part of rather than subclass of Postal Address Address Country Address Locality Address Region Postal Code Post Office Box Number Street Address  In schema.org, the expected type of AddressCountry is a country, whereas the other components of a postal address have expected types of Text (http://schema.org/PostalAddress)

15. Building a Taxonomy – Common Problems 15  Narrower in meaning than rather than subclass of  Logic of Terms Adhesives & Sealants Adhesives Applicators & Dispensers Adhesive Application Services Glue Applicators Epoxy Dispensers Sealants  In Thomasnet.com(http://www.thomasnet.com/browse) classes are formed by conjunctions and the class hierarchy contains examples of subclasses based on search patternshttp://www.thomasnet.com/browse

16. Building a Taxonomy – Common Problems 16  Narrower in meaning than rather than subclass of ColorGreenBrown GreenDark Green Desaturated Green Light Green Saturated Green Yellow Green  In the Phenotypic Quality Ontology (http://purl.obolibrary.org/obo/PATO_0000320) classes are subclasses by hue.

17. Building a Taxonomy – Common Problems 17  Non-Disjoint Classes DayDay of WeekSundayMondayTuesdayWednesdayThursdayFridaySaturdayHolidayAnniversary

18. Building a Taxonomy – Common Problems 18  Different Identity Criteria QualityHeight Height of Person Height of Building Height of Landform Height of Mountain Height of Waterfall

19. Reading 19  Guus Schreiber’s discussion of OWL restrictions at: http://www.cs.vu.nl/~guus/public/owl-restrictions/