1. ONTOLOGY ENGINEERING Lab #2 – September 8, 2014 1

2. Data Definition Languages * from http://www.techonthenet.com/sql/tables/create_table.php 2  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) ); *

3. RDF, RDF-S and OWL 3  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#

4. RDF, RDF-S and OWL 4  rdf:type is used in declarations of a resource being an instance of a given type  owl:Class used in declarations of an entity as a class  rdfs:Datatype used in declarations of an entity as a datatype  owl:ObjectProperty used in declarations of an entity as an object property  owl:DatatypeProperty used in declarations of an entity as a datatype property  owl:AnnotationProperty used in declarations of an entity as an annotation property  owl:NamedIndividual used in declarations of an entity as a named individual

5. RDF, RDF-S, and OWL  Class hierarchies (i.e. taxonomies) can be built by subsuming one named class under another (rdfs:subClassOf)  But we also can use restrictions on other relationships to create subclass and equivalent class relations to anonymous classes Existential Restriction – members of the restricted class must be related via the property to at least one member of the object class Universal Restriction – if a member of the restricted class is related via the property to an entity then that entity must be a member of the object class (need example) 5

6. Enriching a Taxonomy with Restrictions 6  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

7. Enriching a Taxonomy with Restrictions 7  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

8. Necessary and Sufficient Conditions  “All acts of inhabitance are acts performed by persons.” is an expression of a necessary condition to be an act of inhabitance. Other ways to express this are:  If a1 is an act of inhabitance then a1 is performed by a person  If a1 is not an act performed by a person, then a1 is not an act of inhabitance  The class of act of inhabitance is a subclass of act performed by person  This is not, however, an expression of a sufficient condition for being an act of inhabitance  In order for S to be a sufficient condition of N it must be true that if S then N 8

9. Equivalent Classes  Two classes are equivalent if and only if they have the same members  Example: Even Numbers and Numbers divisible by 2  If two classes are equivalent then membership in one is both a necessary and sufficient condition of the other If n is an even number then n is divisible by 2 If n is divisible by 2 then n is an event number  In Protégé,  A Primitive Class is one that has only subclass restrictions (necessary condition)  A Defined Class is one that has equivalent class restriction (necessary and sufficient condition) 9

10.  The conditions of class membership can be expressed by providing a list of the individuals that are its members  e.g. A continent is one of Africa, Asia, Antarctica, Europe, North America, Oceania, South America  The technique can be used for subclass restrictions but seems best suited for equivalent class restrictions  The type of the individuals can be, but need not be, explicitly asserted (rdf:type). If not, it will be inferred by the reasoner Enumerated Classes 10

11. Set Operations on Classes 11  The intersection (and) operand can be used to express that a class is either a subclass of or equivalent to the class of individuals that are members of two or more classes  Example: Customer of the ACME Corporation is a person that has purchased a product from ACME Corporation  Example: A sister is a female sibling  The union (or) operand can be used to express that a class is either a subclass of or equivalent to the class of individuals that are members of any of two or more classes  Example: An agent is either a person or organization  Example: New York State misdemeanors are either Class A or Class B

12. Set Operations on Classes 12  The Complement (non-) operand can be used to express that class is a subclass of or equivalent to the class of individuals that are not members of one or more classes  Example: A Violation in NYS is any offence, other than a traffic infraction, for which a sentence to a term of imprisonment in excess of 15 days cannot be imposed  Example: Industrial diamonds are unsuitable for use as gemstones

13. Assignment 13  Add constraints from Table 2-1: Relationship between Functional Classification and Travel Characteristics in the Highway Functional Classification Concepts, Criteria and Procedures to your classes of roadway types.  Some of the constraints will be difficult, if not impossible, to describe until we cover some additional techniques. Add enough constraints so that you’re comfortable with the techniques we’ve covered in this lab.