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Ontology Engineering

Lab #2 – September 9, 2013

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Review – Ontology Identifiers and Versioning

Ontology 1.0

Ontology IRI

Ontology 1.1

Ontology 1.2

Ontology 1.n

Version 1.0 IRIVersion 1.1 IRIVersion 1.2 IRI Version 1.n IRI

Current Version

accessible by

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Review – Violations of Versioning Uniqueness Constraints

Ontology 1Ontology IRI: XXXXX

Ontology 2

Ontology 1Ontology IRI: XXXXX

Ontology 2Version IRI: YYYYY

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Data Definition Languages 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 tablesCREATE 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

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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# RDF-S: http://www.w3.org/2000/01/rdf-schema# OWL: http://www.w3.org/2002/07/owl#

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Well Formed Expressions 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

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RDF Graphs

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

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A Couple of Rules for RDF Statements 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:<http://www.buffalo.edu/IE500/rjr9/OEF13_000013> <http://www.buffalo.edu/IE500/rjr9/OEF13_000108> <http://www.buffalo.edu/IE500/rjr9/OEF13_000072>

And the statement: The URL of UB’s website is http://www.buffalo.edu/ will look like:<http://www.buffalo.edu/PHI598/rjr9/OEF13_001158> <http://www.buffalo.edu/PHI598/rjr9/OEF13_000002>"http://www.buffalo.edu/"

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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

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1st (poor) Attempt at “Ontologizing” the Customer Table

Customer

Zip Code

State

City

AddressCustom

er Name

Customer ID

has ZIP code

has ID

has name has address

has City

has State

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Improved Attempt at Ontologizing

Customer

Zip Code

State

City

Address

Person Name

Customer ID

located in

agent in has role

designates

participates in

designates

Person

Act Of Inhabita

nce

Facility

Geospatial

RegionLand Lot

designates

designates

part of near

part of

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Enriching a Taxonomy with Restrictions 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

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Enriching a Taxonomy with Restrictions 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

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Building a Taxonomy – Common Problems Use – Mention Errors Part of rather than subclass of

Postal Address

Address

Country

Address

Locality

Address

Region

Postal Code

Post Office Box

Number

Street Addres

s

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)

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Building a Taxonomy – Common Problems Narrower in meaning than rather than

subclass of Logic of Terms

Adhesives & Sealants

AdhesivesApplicators & DispensersAdh

esive

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 patterns

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Building a Taxonomy – Common Problems Narrower in meaning than rather than

subclass of Color

Green

Brown Green

Dark Green

Desaturate

d Green

Light Green

Saturated

Green

Yellow Green

In the Phenotypic Quality Ontology (http://purl.obolibrary.org/obo/PATO_0000320) classes are subclasses by hue.

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Building a Taxonomy – Common Problems Non-Disjoint Classes

Day

Day of Week

Sunday

Monday

Tuesday

Wednesday

Thursday

Friday

Saturday

Holiday Anniversary

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Building a Taxonomy – Common Problems Different Identity Criteria

Quality

Height

Height of Person

Height of Building

Height of Landform

Height of

Mountain

Height of

Waterfall

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Reading Guus Schreiber’s discussion of OWL

restrictions at: http://www.cs.vu.nl/~guus/public/owl-restrictions/