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Ontology, Semantic Web and DBpedia

study notes about Semantic Web

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Ontology, Semantic Web and DBpedia

  1. 1. 10/8/2009 1 Ontology, Semantic Web  and  Global Database   10/9/2009 1 Creative Commons - BY-NC Contents • Ontology? Why? P tѐ ѐ• Protѐgѐ • Semantic Web • Linked Open Data 10/9/2009 2Creative Commons - BY-NC
  2. 2. 10/8/2009 2 Syntactic Web   10/9/2009 Creative Commons - BY-NC 3 Problems A typical web page is  designed with markup  language ,HTML,  which is designed for  rendering  presentation and  Hyperlink to related  information. Semantic  content is accessiblecontent is accessible  to humans but not to  computers.   10/9/2009 Creative Commons - BY-NC 4
  3. 3. 10/8/2009 3 Linguistic Concept ReferentForm Concept Relates toActivates 10/9/2009 Creative Commons - BY-NC 5 Tank Stands for ? Problems • Keyword‐based Search S d H• Synonyms and Homonyms • No Parameter Search • No Cross Silos Data Extraction or Comparison • No Unified View and/or Interpretation of Data • Limited Ability to Re‐use of Datay • Difficult to Share Data with Business Partners 10/9/2009 Creative Commons - BY-NC 6
  4. 4. 10/8/2009 4 Need to Add “Semantics” • Using Ontology to specify the meaning of  annotationannotation. – Ontology provides a set of vocabulary terms – New terms can be defined with existing ones – Meaning of each term can be formally specified – The relationship between terms can be defined 10/9/2009 Creative Commons - BY-NC 7 Web • Web 1.0 – links documents to documents W b 2 0 id t t f• Web 2.0 – provides contents from users • Web 3.0 – links data to data 10/9/2009 Creative Commons - BY-NC 8
  5. 5. 10/8/2009 5 What is Ontology?  http://en.wikipedia.org/wiki/Ontology_%28information_science%29 • In computer science and information science, an  ontology is a formal representation of a set ofontology is a formal representation of a set of  concepts within a domain and the relationships  between those concepts. It is used to reason about  the properties of that domain, and may be used to  define the domain.  • An ontology is a formal, explicit specification of a  conceptualization.  10/9/2009 Creative Commons - BY-NC 9 XML (Extensible  Markup Language) It is a textual data format,  with strong support via  Unicode for the languages Well‐formed and error‐handling • It contains only properly‐encoded legal  Unicode characters.  None of the special  syntax characters such as "<" and "&"  appear except when performing their  markup‐delineation roles. • The begin, end, and empty‐elementUnicode for the languages  of the world. Although  XML’s design focuses on  documents, it is widely  used for the  representation of arbitrary  data structures. The begin, end, and empty element  tags which delimit the elements are  correctly nested, with none missing and  none overlapping. • The element tags are case‐sensitive; the  beginning and end tags must match  exactly. • There is a single "root" element which  contains all the other elements. 10/9/2009 Creative Commons - BY-NC 10
  6. 6. 10/8/2009 6 XSD  (XML Schema) XSD datatypes ‐1/2 • xsd:string,  • xsd:boolean,  • xsd:decimal,  • xsd:float,  • xsd:double,  • xsd:dateTime,  d i XSD can be used to express  a set of rules to which an  XML document must XSD datatypes ‐2/2 • xsd:language,  • xsd:NMTOKEN,  • xsd:Name,  • xsd:NCName, • xsd:integer, • xsd:nonPositiveInteger, • xsd:time,  • xsd:date,  • xsd:gYearMonth,  • xsd:gYear,  • xsd:gMonthDay,  • xsd:gDay,  • xsd:gMonth,  • xsd:hexBinary,  • xsd:base64Binary XML document must  conform in order to be  considered 'valid'  according to that schema.  However, unlike most  other schema languages,  XSD was also designed  with the intent that  xsd:nonPositiveInteger, • xsd:negativeInteger,  • xsd:long,  • xsd:int,  • xsd:short, • xsd:byte, • xsd:nonNegativeInteger, • xsd:unsignedLong, d i dIxsd:base64Binary,  • xsd:anyURI,  • xsd:normalizedString,  • xsd:token,  determination of a  document's validity would  produce a collection of  information adhering to  specific data types. 10/9/2009 Creative Commons - BY-NC 11 • xsd:unsignedInt, • xsd:unsignedShort, • xsd:unsignedByte, • xsd:positiveIntegers RDF (Resource  Descriptive  Framework) RDF vocabulary • rdf:type • rdf:Property • rdf:XMLLiteral • rdf:nil • rdf:List RDF describes statements  about resources, in  particular Web resources • rdf:Statement • rdf:subject • rdf:predicate • rdf:object • rdf:first • rdf:rest • rdf:Seq particular, Web resources,  in the form of subject‐ predicate‐object  expressions. These  expressions are known as  triples in RDF terminology.  rdf:Seq • rdf:Bag • rdf:Alt • rdf:_1  • rdf:_2 ...  • rdf:value 10/9/2009 Creative Commons - BY-NC 12
  7. 7. 10/8/2009 7 Triples and Graph The base element of the  RDF model is the triple:  • a resource (the subject)• a resource (the subject) • inks (the predicate)   • another resource (the  object)  A resource <subject> has a  property <predicate>  valued by <object>. 10/9/2009 Creative Commons - BY-NC 13 <subject> <predicate> <object> Pro and Cons of RDF • Pros U i l d t d l ( t XML bj t d l ti l– Universal data model (map to XML, object and relational  model) – Additive, easy to merge multiple RDFs – Predicate logic (like prolog) – Use URI to identify  a resource • ConsCons – Lacks  of concepts of enumeration – Lacks data types – No Object‐Oriented Features 10/9/2009 Creative Commons - BY-NC 14
  8. 8. 10/8/2009 8 Resource (RDFS) Classes • rdfs:Resource • rdfs:Literal • rdfs:Class • rdfs:Datatype df C i RDF Schema (RDFS) is an  extensible knowledge  representation language Properties • rdfs:subClassOf • rdfs:subPropertyOf • rdfs:domain • rdfs:range • rdfs:label df t• rdfs:Container • rdfs:ContainerMe mbershipProperty • rdf:List • rdf:Statement • rdf:Bag • rdf:Seq representation language,  providing basic elements  for the description of  ontologies, otherwise  called Resource  Description Framework  (RDF) vocabularies,  intended to structure RDF  • rdfs:comment • rdfs:member • rdfs:seeAlso • rdfs:isDefinedBy • rdf:first • rdf:rest • rdf:type • rdf:valuerdf:Seq • rdf:Alt • rdf:XMLLiteral • rdf:Property resources. 10/9/2009 Creative Commons - BY-NC 15 • rdf:subject • rdf:predicate • rdf:object Web Ontology Language  10/9/2009 Creative Commons - BY-NC 16
  9. 9. 10/8/2009 9 Web Ontology Language (OWL) • Extends RDF/RDFS to support complex knowledge  representationrepresentation. • An OWL ontology may include descriptions of  classes, properties and their instances. • Open‐World assumption – what is not known is not  “untrue”, it is just “unknown”. 10/9/2009 Creative Commons - BY-NC 17 OWL‐1 • OWL‐Lite S t i l l ifi ti ll l di liti– Support simple classification, allows only cardinalities  (member count) of 1 and 0 and only minimal constraints.  • OWL‐DL (Descriptive Language) – Supports more complex ontologies, but with guarantees,  such as processing finishing in finite time, restricting  elements to be one type. • OWL‐Full – Full support for maximum freedom of RDF, with no  computational guarantees. 10/9/2009 Creative Commons - BY-NC 18
  10. 10. 10/8/2009 10 OWL Classes and Properties  partial list, see http://www.w3.org/TR/owl‐guide/ for full list • Class – owl:class • Property Restrictions – owl:allValuesFrom – rdfs:subClassOf • Property – owl:ObjectProperty – owl:DataProperty – rdfs:subPropertyOf – rdfs:domain – rdfs:range • Property Characteristic – owl:someValuesFrom – owl:cardinality – owl:someValue • Equivalence – owl:EquivalenceClass – owl:EquivalenceProperty – owl:sameAs • Complex Classesp y – owl:TransitiveProperty – owl:FunctionalProperty – owl:InverseProperty – owl:InverseFunctionalProperty p – owl:IntersectionOf – owl:UnionOf – owl:CompoundOf 10/9/2009 Creative Commons - BY-NC 19 Semantic Web Layer Cake From: http://www.semanticfocus.com/blog/entry/title/introduction‐to‐the‐semantic‐web‐vision‐ and‐technologies‐part‐1‐overview/ 10/9/2009 Creative Commons - BY-NC 20
  11. 11. 10/8/2009 11 Tools • RDF/OWL Editors P tѐ ѐ T b id– Protѐgѐ, Topbraid, … • RDF Store – SwiftOWLIM, AllegroGraph, OpenLink Virtuoso, … • Query – SPARQL • Reasoners – Pellet, FaCT++, … 10/9/2009 Creative Commons - BY-NC 21 10/9/2009 Creative Commons - BY-NC 22
  12. 12. 10/8/2009 12 Protѐgѐ Overview • Stanford Center for Biomedical Informatics Research,  – Stanford UniversityStanford University  – University of Manchester • OWL Editor • Plugins: Natural Language, Visualization,  Rules Engine,  Database, … • Very well documented,  • Long history with many academic supports 10/9/2009 Creative Commons - BY-NC 23 Protѐgѐ – Class View  10/9/2009 Creative Commons - BY-NC 24
  13. 13. 10/8/2009 13 Protѐgѐ – Object Property View   10/9/2009 Creative Commons - BY-NC 25 Protѐgѐ – Value Property View  10/9/2009 Creative Commons - BY-NC 26
  14. 14. 10/8/2009 14 Protѐgѐ ‐ Visualization  10/9/2009 Creative Commons - BY-NC 27 Ontology Development • Define purpose and scopes Eli it k l d• Elicit knowledge • Collect and organize concepts • Classify and add axioms • Reasoning  10/9/2009 Creative Commons - BY-NC 28
  15. 15. 10/8/2009 15 OWL vs. UML class modeling • OWL properties vs. UML associations & attributes OWL ti h di ti– OWL properties have a direction – OWL properties are binary relations – OWL properties are “first‐class” citizens (global scope) • OWL classes vs. UML classes – OWL classes have no operations OWL classes can have “sufficient” conditions– OWL classes can have  sufficient  conditions • Primitive vs. defined classes 2910/9/2009 Creative Commons - BY-NC Ontologies and Data Models • Ontologies live in an open, distributed world; data  models in a closed worldmodels in a closed world • Writing a model in OWL does not make it an  ontology – The ontology should be shared 3010/9/2009 Creative Commons - BY-NC
  16. 16. 10/8/2009 16 Semantic Web 10/9/2009 Creative Commons - BY-NC 31 Web Technologies from http://www.abricocotier.fr/5694‐les‐trois‐grandes‐etapes‐de‐levolution‐du‐web 10/9/2009 Creative Commons - BY-NC 32
  17. 17. 10/8/2009 17 Benefit Semantic Web Applications • Less coding, more meaningful data structure L b i l• Less business rules • More across boundary information • Embedded logic 10/9/2009 Creative Commons - BY-NC 33 Global Database from: Tim Berners‐Lee, Weaving the Web, 1999 • "If HTML and the Web made all the online  documents look like one huge book RDF schemadocuments look like one huge book, RDF, schema,  and inference languages will make all the data in the  world look like one huge database" 10/9/2009 Creative Commons - BY-NC 34
  18. 18. 10/8/2009 18 nternetnternetmemeto the Into the In 10/9/2009 Creative Commons - BY-NC 35 WelcomWelcom One Global Machine 10/9/2009 Creative Commons - BY-NC 36
  19. 19. 10/8/2009 19 Dimension of Global Machine From: http://www.kk.org/thetechnium/archives/2007/11/dimensions_of_t.php 170 quadrillion (170 * 10^15) Transistors 55 trillion (55* 10^12) Links55 trillion (55  10 12) Links 2 megahertz Emails 31 kilohertz Text Messages 162 kilohertz Instance Messages 14 kilohertz Search 246 exabyte Storage 9 exabyte (9 * 10^18) RAM 9 terabyes/second Bandwidth 800 billion kwh/year Power consumption 10/9/2009 Creative Commons - BY-NC 37 10/9/2009 38Creative Commons - BY-NC
  20. 20. 10/8/2009 20 10/9/2009 Creative Commons - BY-NC 39 DBpedia • Structure multiple wikipedia information to allow  query directlyquery directly • Build from scratch, 170 classes, 900 properties • Serves as hub for other databases 10/9/2009 Creative Commons - BY-NC 40
  21. 21. 10/8/2009 21 Multilingual  Abstracts – English: 2,613,000 g , , – German: 391,000  – French: 383,000  – Dutch: 284,000  – Polish: 256,000  – Italian: 286,000  – Spanish: 226,000  10/9/2009 Creative Commons - BY-NC 41 – Japanese: 199,000  – Portuguese: 246,000  – Swedish: 144,000  – Chinese: 101,000 Sept 2008 May 2007 April 2008 2 billion RDF triples 10/9/2009 Creative Commons - BY-NC 42 May 2007 500 million  RDF triples
  22. 22. 10/8/2009 22 Linked Open Database March 2009 4.5 billion  RDF triples 180 data million links Online ActivitiesMusic Online Activities PublicationsGeographic Cross-Domain 10/9/2009 Creative Commons - BY-NC 43 Life Sciences Open Questions • Architecture Impact D i A li ti• Device Applications • Device Management • Data Structure and Management • Software Evolution, new requirements • Competitor’s offersp • … 10/9/2009 Creative Commons - BY-NC 44
  23. 23. 10/8/2009 23 Thank You for Your Attention 10/9/2009 Creative Commons - BY-NC 45

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  • KingColdPrime

    May. 6, 2017

study notes about Semantic Web

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