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CSCE 790 - Ontology Development Lecture 03 Semantic Web CSCE 510 April 29, 2013 Figure from Model Driven Architecture and Ontology Development.

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Presentation on theme: "CSCE 790 - Ontology Development Lecture 03 Semantic Web CSCE 510 April 29, 2013 Figure from Model Driven Architecture and Ontology Development."— Presentation transcript:

1 CSCE Ontology Development Lecture 03 Semantic Web CSCE 510 April 29, 2013 Figure from Model Driven Architecture and Ontology Development

2 Outline - CSCE 790C Slide Protege  Pragmatics  Assignments, Papers, and Projects instead of exams  Ontologies  medical ontologies, UML, Snowmed, …Gene ontology  Wordnet, Framenet, Verbnet, SUMO  Tools: protégé, reasoners – pellet, fact++, …  Ontology Languages: RDF, OWL, OWL-lite, OWL 2.0  Reasoning about ontologies: consistency  Reasoning with Ontologies  Semi-automatic construction

3 Semantic Web - CSCE 790C Slide Semantic Web  W3C RDF and OWL Activities  The Semantic Web is a framework for sharing data between companies, applications, enterprises, communities, and people, independent of platform and software.  RDF and OWL are key Semantic Web technologies.  RDF - Resource Description Framework  RDF is a language for describing Web resources, such as the title, author, modification date, content, and copyright information of a Web page.  OWL - Web Ontology Language  OWL is built on top of RDF, and is a language for processing information on the internet.  If you want to learn more about OWL, please visit W3Schools' RDF Tutorial.W3Schools' RDF Tutorial  SPARQL - Query Language for RDF  SPARQL offer developers a way to write queries across the wide range of RDF information on the internet.  W3C Specifications and Timeline

4 Uniform Resource Identifier (URI) - CSCE 790C Slide Semantic Web  a uniform resource identifier (URI) is a string of characters used to identify a name or a web resource.string charactersidentifyweb resource  Not to be confused with its two subclasses:  uniform resource locator (URL) anduniform resource locator  uniform resource name (URN) uniform resource name

5 - CSCE 790C Slide Semantic Web

6 examples - CSCE 790C Slide Semantic Web  URLs   URN urn:isbn: is a URI that specifies the identifier system, i.e. international standard book number (ISBN)ISBN  A URL is simply a URI that happens to point to a physical resource over a network

7 URI Syntax - CSCE 790C Slide Semantic Web  : [ ? ] [ #  scheme name consists of a sequence of characters beginning with a letter  hierarchical part of the URI begins with “//”  authority part holds an optional user-information part, terminated with  path part, if present, must begin with a forward slash ("/")  query is an optional part, separated by a question mark ("?"), generally a sequence of = pairs query

8 - CSCE 790C Slide Semantic Web  The following figure displays two example URIs er/there/index.dtb?type=animal&name=narwhal#n ose and urn:example:animal:ferret:nose)

9 Resource Description Framework (RDF) - CSCE 790C Slide Semantic Web  Resource Description Framework (RDF) is a family of World Wide Web Consortium (W3C) specificationsWorld Wide Web Consortiumspecifications  triples: subject-predicate-object; originally designed as a metadata data modelmetadata data model  now a general method for conceptual description or modeling of information that is implemented in web resourcesweb resources  similar to classic conceptual modeling approaches such as entity– relationship or class diagramsentity– relationshipclass diagrams 

10 RDF - the Basis of the Semantic Web - CSCE 790C Slide Semantic Web  Fundamental Concepts of Chapter 3  RDF (Resource Description Framework)  Triple subject-predicate-object  Graph – structural view of RDF data  Merging  URI (Uniform Resource Indicator)  namespace – namespaces allow different agents to use the same word in different ways  qname – abbreviated URI of the form - namespace : name  rdf: type – relationship between instance and its type  rdf:Property – thetype of any property in RDF  reification – making statement about another stmt using ref:subject, rdf:predicate, rdf:object  N-triples, N3, RDF/XML  blank nodes (no URI) stand for anonymous entries From p57 Semantic Web for the Working Ontologist by Allemang &Hendler

11 Example 1: RDF Description of a person named Eric Miller - CSCE 790C Slide Semantic Web

12 What is RDF? Resource Description Framework - CSCE 790C Slide Semantic Web  What is RDF?  RDF is a framework for describing resources on the web  RDF is designed to be read and understood by computers  RDF is not designed for being displayed to people  RDF is written in XML  RDF is a part of the W3C's Semantic Web Activity  RDF is a W3C Recommendation  RDF - Examples of Use  Describing properties for shopping items, such as price and availability  Describing time schedules for web events  Describing information about web pages (content, author, created and modified date)  Describing content and rating for web pictures  Describing content for search engines  Describing electronic libraries From

13 Try 2 Figure 4-2 Sample RDF triples - CSCE 790C Slide Semantic Web  Figure 4.2 from Semantic Web for the Working Ontologist by Allemang &Hendler

14 RDF Statements - CSCE 790C Slide Semantic Web  “The combination of a Resource, a Property, and a Property value forms a Statement (known as the subject, predicate and object of a Statement).  Let's look at some example statements to get a better understanding:  Statement: "The author of is Jan Egil Refsnes".  The subject of the statement above is:  The predicate is: author  The object is: Jan Egil Refsnes  Statement: "The homepage of is  The subject of the statement above is:  The predicate is: homepage  The object is: From

15 - CSCE 790C Slide Semantic Web  The resource "http://www.w3.org/People/EM/contact#me" is the subject.http://www.w3.org/People/EM/contact#me  The objects are:  "Eric Miller" (with a predicate "whose name is"),  (with a predicate "whose address is"), and  "Dr." (with a predicate "whose title is").  The subject is a URI.  The predicates also have URIs. For example, the URI for each predicate:  "whose name is" is  "whose address is" is  "whose title is" is  In addition, the subject has a type (with URI syntax-ns#type), which is person (with URI and a mailbox (with URI syntax-ns#type  Therefore, the following "subject, predicate, object" RDF triples can be expressed:  "Eric Miller"  "Dr."  ns#type, ns#typehttp://www.w3.org/2000/10/swap/pim/contact#Person 

16 - CSCE 790C Slide Semantic Web Example 2: The postal abbreviation for New York  Certain concepts in RDF are taken from logic and linguistics, where subject-predicate and subject-predicate-object structures have meanings similar to, yet distinct from, the uses of those terms in RDF. This example demonstrates:logiclinguistics  In the English language statement 'New York has the postal abbreviation NY', 'New York' would be the subject, 'has the postal abbreviation' the predicate and 'NY' the object.English language  Encoded as an RDF triple, the subject and predicate would have to be resources named by URIs. The object could be a resource or literal element. For example, in the Notation 3 form of RDF, the statement might look like: Notation 3  "NY".  In this example, "urn:x-states:New%20York" is the URI for a resource that denotes the US state New York, "http://purl.org/dc/terms/alternative" is the URI for a predicate (whose human-readable definition can be found at here [18] ), and "NY" is a literal string. Note that the URIs chosen here are not standard, and don't need to be, as long as their meaning is known to whatever is reading them.New York [18]  N-Triples is just one of several standard serialization formats for RDF. The triple above can also be equivalently represented in the standard RDF/XML format as: N-Triplesserialization  NY  However, because of the restrictions on the syntax of QNames (such as dcterms:alternative above), there are some RDF graphs that are not representable with RDF/XML.QNames

17 - CSCE 790C Slide Semantic Web  Example 3: A Wikipedia article about Tony Benn  In a like manner, given that "http://en.wikipedia.org/wiki/Tony_Benn" identifies a particular resource (regardless of whether that URI could be traversed as a hyperlink, or whether the resource is actually the Wikipedia article about Tony Benn), to say that the title of this resource is "Tony Benn" and its publisher is "Wikipedia" would be two assertions that could be expressed as valid RDF statements. In the N-Triples form of RDF, these statements might look like the following: WikipediaTony BennN-Triples  "Tony Benn". "Wikipedia".  And these statements might be expressed in RDF/XML as:  Tony Benn Wikipedia  To an English-speaking person, the same information could be represented simply as:  The title of this resource, which is published by Wikipedia, is 'Tony Benn'

18 Namespaces - CSCE 790C Slide Semantic Web Ref ???

19 Extensible Markup Language (XML) - CSCE 790C Slide Semantic Web  (XML) is a markup language that defines a set of rules for encoding documentsmarkup language  format that is designed to be both human-readable and machine-readable. formathuman-readable machine-readable  XML Schema is a schema language for XML, described by the W3C as the successor of DTDs  Tag - a markup construct that begins with.  Tags come in three flavors:  start-tags; for example:  end-tags; for example:  empty-element tags; for example:

20 HTML versus XML - CSCE 790C Slide Semantic Web Model Driven Architecture and Ontology Development Gasevic et al

21 Example XML Schema - CSCE 790C Slide Semantic Web Figure from Model Driven Architecture and Ontology Development Gasevic et al

22 RDF and RDF Schema - CSCE 790C Slide Semantic Web  XML provides syntax  “but XML does not provide data interpretation”  Data interpretation can be handled by RDF and RDF schema Model Drivien Architecture and Ontology Development Gasevic et al

23 - CSCE 790C Slide Semantic Web Model Driven Architecture and Ontology Development Gasevic et al Figure from Model Driven Architecture and Ontology Development Gasevic et al

24 - CSCE 790C Slide Semantic Web Figure from Model Driven Architecture and Ontology Development Gasevic et al

25 DAML+OIL Web Ontology Language - CSCE 790C Slide Protege Figure from Model Driven Architecture and Ontology Development Gasevic et al

26 - CSCE 790C Slide Semantic Web Figure from Model Driven Architecture and Ontology Development Gasevic et al

27 Semantic Web Languages - CSCE 790C Slide Semantic Web  URI – Uniform Resource Indicator  Resource Description Framework (RDF)  XML is a meta-language for representing Semantic Web languages  XML namespaces Model Driven Architecture and Ontology Development Gasevic et al

28 Tim Berners-Lee’s Semantic web layer-cake - CSCE 790C Slide Protege Figure from Model Driven Architecture and Ontology Development Gasevic et al

29 The Genesis of OWL - CSCE 790C Slide Semantic Web

30 XML and XML Schema - CSCE 790C Slide Protege   XML Schema Example

31 What is an XML Schema? - CSCE 790C Slide Semantic Web  The purpose of an XML Schema is to define the legal building blocks of an XML document, just like a DTD.  An XML Schema:  defines elements that can appear in a document  defines attributes that can appear in a document  defines which elements are child elements  defines the order of child elements  defines the number of child elements  defines whether an element is empty or can include text  defines data types for elements and attributes  defines default and fixed values for elements and attributes

32 Well-Formed is not Enough - CSCE 790C Slide Semantic Web  “A well-formed XML document is a document that conforms to the XML syntax rules, like:  it must begin with the XML declaration  it must have one unique root element  start-tags must have matching end-tags  elements are case sensitive  all elements must be closed  all elements must be properly nested  all attribute values must be quoted  entities must be used for special characters  Even if documents are well-formed they can still contain errors, and those errors can have serious consequences.  Think of the following situation: you order 5 gross of laser printers, instead of 5 laser printers. With XML Schemas, most of these errors can be caught by your validating software.”

33 - CSCE 790C Slide Semantic Web

34 What is OWL? - CSCE 790C Slide Semantic Web  OWL stands for Web Ontology Language  OWL is built on top of RDF  OWL is for processing information on the web  OWL was designed to be interpreted by computers  OWL was not designed for being read by people  OWL is written in XML  OWL has three sublanguages  OWL is a W3C standard

35 Why OWL? - CSCE 790C Slide Semantic Web  OWL is a part of the "Semantic Web Vision" - a future where:  Web information has exact meaning  Web information can be processed by computers  Computers can integrate information from the web  OWL was Designed for Processing Information  OWL was designed to provide a common way to process the content of web information (instead of displaying it).  OWL was designed to be read by computer applications (instead of humans).  OWL is Different from RDF  OWL and RDF are much of the same thing, but OWL is a stronger language with greater machine interpretability than RDF.  OWL comes with a larger vocabulary and stronger syntax than RDF.  OWL Sublanguages  OWL Lite  OWL DL (includes OWL Lite)  OWL Full (includes OWL DL) From

36 OWL - CSCE 790C Slide Semantic Web … …. Figure from Model Driven Architecture and Ontology Development Gasevic et al

37 OWL 2 Web Ontology Language Document Overview (2nd Edition) - CSCE 790C Slide Semantic Web  pdf version  Table of Contents  1 Introduction 1 Introduction  2 Overview 2 Overview  2.1 Ontologies 2.1 Ontologies  2.2 Syntaxes 2.2 Syntaxes  2.3 Semantics 2.3 Semantics  2.4 Profiles 2.4 Profiles  3 Relationship to OWL 1 3 Relationship to OWL 1  4 Documentation Roadmap 4 Documentation Roadmap  5 Appendix: Change Log (Informative) 5 Appendix: Change Log (Informative)  5.1 Changes Since Recommendation 5.1 Changes Since Recommendation  5.2 Changes Since Proposed Recommendation 5.2 Changes Since Proposed Recommendation  5.3 Changes Since Last Call 5.3 Changes Since Last Call  6 Acknowledgements 6 Acknowledgements  7 References 7 References

38 OWL 2 Web Ontology Language Document Overview (2nd Edition) - CSCE 790C Slide Semantic Web

39 Snippet of References from OWL Overview - CSCE 790C Slide Semantic Web


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