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Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF, linked data and semantic webDepartamento de InformáticaUniversidad de OviedoJose Emilio Labra Gayo

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraAbout meMain researcher WESO research group (WEb Semántics Oviedo)Author of the following books:http://www.di.uniovi.es/~labraWeb Semántica (2012) Validating RDF Data (2017)

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraStructure of presentationWhy RDF?RDF data modelRDF ecosystemRDF applicationsInference systems: RDFS, OWLSPARQLChallenges

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraWhy RDF?

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labra

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraThe flood of dataProducing data is more and more easyOpen trendsOpen SoftwareOpen ContentOpen DataOpen ScienceOpen GovernmentOld models are affectedMúsic, Films, finance,...EducationGovernment ...

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraWhy?Reasons for governmentsTransparencyLeadershipGovernment as catalyzerPromote participationNew initiatives and appsReasons for citizensData belong to usCreated with public moneyWe want better services

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraOK, long live to data!but…

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraProblems of current webIt is not enough to publish dataIt must be foundIf not found, as if it doesn't existIt must be usableIf not usable, it is worthlessReuse data in unexpected contexts

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraSemantic lossWhen publishing data, some semantics is lostThe person that wants to publish has more info about the dataSome info is lost during the publication processpublisherparty nextsaturdayFormats:HTML, PDF, JPG,...consumer(person)consumer(agent)party nextsaturdaySemantics9/Dec/2017Datapublished

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraHTML doesn't have enough semanticsHTML is intended to publish hypertextHTML tags are understood by browsersInformation inside tags = natural languageMachines don't understand natural language yetEvent:<ul><li>Name: Concert</li><li>Date: Next saturday</li></ul>իրադարձություն:<ul><li>տիպ: համերգ</li><li>ամսաթիվ: հաջորդ շաբաթ/li></ul>

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraXML problemXML goes a step forwardSpecific vocabularies have meaning in some specific contextSpecific applications can process XML documentsXML documents are difficult to integrate if they are from different domains<event><name>համերգ</name><date>հաջորդ շաբաթ</date></event><event><name>Concert</name><date>Next saturday</date></event><իրադարձություն><տիպ>համերգ</տիպ><ամսաթիվ>հաջորդ շաբաթ</ամսաթիվ></իրադարձություն>

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraJson problemJSON is almost the same as XMLIt may be easier to parse and processby developersBut the meaning depends on each domainIt is even worse as there are no namespaces or validation{"event": {"name": "Party" ,"date": "Next saturday"}}{"event": {"name": "համերգ" ,"date": "հաջորդ շաբաթ"}}{"իրադարձություն": {"տիպ": "համերգ" ,"ամսաթիվ": "հաջորդ շաբաթ"}}

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraTowards semantic webSemantic web = vision of the data webTim Berners LeeSource: WikipediaGoal: Share and Reuse data between applications, and communitiesFrom a web of documents to a web of data

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraBenefitsAccessible dataAvoid semantic lossFacilitate task automationLinked dataData reuseApplication integrationThe best way to use your data will befound by other peopleJo Walsh, Rufus Pollock, http://www.okfn.org/files/talks/xtech_2007/

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraWeb featuresNon centralizedDifficult to ensure data integrity and qualityDynamic informationInformation is constantly changingBig amounts of informationBig data3Vs: Volume, Velocity, VarietyOpen systemAAA lemma: Anyone can say Anything about Any topic

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraBiggest challenge = IntegrationIn general, the challenge is not tocomputerize somethingThe challenge is integrate systemsInteroperabilityIt is not enough to publish data…

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraPublish = make something accessibleAccessibility levelsPhysical disabilityTechnical disability: other environmentsCultural and intellectualIlliteracyKnowledge barriersOther languages…Accessible to machines

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraStar model*★ Publish data(any format)★★ Use structured formats(Excel instead of scanned pictures)★★★ Non proprietary structured formats(CSV instead of Excel)★★★★ Use URIs to identify data(other systems can link to our data)★★★★★ Link to other data(provide contextual information)* Tim Berners-Lee, Gov 2.0 Expo 2010http://www.youtube.com/watch?v=ga1aSJXCFe0

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraUnstructured formatsBlack box formats: Pictures, video, audio, etc.Binary formats: PDF, PS, etc.They require low level techniques, patternrecognition, signal processing, etc★

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraStructured formatsData have some structureExample: ExcelProblem with proprietary formatsMay require non-free tools★ ★

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraNon-proprietary formatsUse open-structured formatsExamples: CSV, HTMLProblem: Content depends on context★ ★ ★

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraURIs identify dataUse URIs to identify dataContent negotiation can provide different representations★ ★ ★ ★Example

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraExample: RDF ★ ★ ★ ★<http://www.sepe.es/data/unemployment/Asturias/Allande/2013/10>HTML?@prefix sepe: <http://www.sepe.es/datos/>sepe:obs1 sepe:municipality "Allande" ;sepe:unemployees 18 .RDF?

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraLink with other dataRepresentations return links to other dataIt allos to:Reuse and find other dataUnforeseen applications★ ★ ★ ★ ★

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraLinked data example ★ ★ ★ ★ ★<http://www.sepe.es/data/unemployment/Asturias/Allande/2013/10>HTML?@prefix sepe: <http://www.sepe.es/data/>sepe:obs1 sepe:municipality dbo:allande;sepe:unemployees 23 .RDF?dbo:allande dbo:areaTotal 342.24 ;rdf:type <http:/.../municipalitiesInAsturias> ;dbo:country <http:/.../Spain> ;dbo:populationTotal 2106 ;. . .

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraLinked Open Data principles1. Use URIs to denote things2. Use HTTP URIs so that people can look up those names3. When someone looks up a URI, provide useful information, using thestandards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things.★ ★ ★ ★ ★

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraLinked open data (2007)

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraLinked open data (2017)Fuente: "Linking Open Data cloud diagram 2017, by Andrejs Abele, John P. McCrae, Paul Buitelaar, Anja Jentzsch and Richard Cyganiak. http://lod-cloud.net/"

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF Data Model

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraShort history of RDFRDF: Resource Description FrameworkAround 1997 - PICS, Dublin core, Meta Content Framework1997 1st Working draft https://www.w3.org/TR/WD-rdf-syntax-971002RDF/XML1999 1st W3C Rec https://www.w3.org/TR/1999/REC-rdf-syntax-19990222/XML Syntax, first applications RSS, EARL2004 - RDF Revised https://www.w3.org/TR/2004/REC-rdf-concepts-20040210/Emergence of SPARQL, Turtle, Linked Data2014 - RDF 1.1 https://www.w3.org/TR/rdf11-concepts/SPARQL 1.1, JSON-LD2017 - RDF validation: SHACL/ShEx

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF Data ModelRDF is made from statementsStatment = a triple (subject, predicate, object)Example:http://example.org/alicehttp://example.org/bobhttp://schema.org/knowssubject predicate object<http://example.org/alice> <http://schema.org/knows> <http://example.org/bob> .N-Triples representationsubject objectpredicate

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraSet of statements = RDF graphRDF data model = directed graphExample:http://example.org/aliceex:bobhttp://example.org/carolhttp://example.org/bobhttp://schema.org/knowshttp://schema.org/knowshttp://schema.org/knowshttp://schema.org/knowsN-triples representation<http://example.org/alice> <http://schema.org/knows> <http://example.org/bob> .<http://example.org/bob> <http://schema.org/knows> <http://example.org/carol> .<http://example.org/carol> <http://schema.org/knows> <http://example.org/alice> .<http://example.org/carol> <http://schema.org/knows> <http://example.org/bob> .subject predicate object

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraTurtle notationHuman readable notation that simplifies N-TriplesAllows namespace declarations<http://example.org/alice> <http://schema.org/knows> <http://example.org/bob> .<http://example.org/bob> <http://schema.org/knows> <http://example.org/carol> .<http://example.org/carol> <http://schema.org/knows> <http://example.org/alice> .<http://example.org/carol> <http://schema.org/knows> <http://example.org/bob> .prefix : <http://example.org/>prefix schema: <http://schema.org/>:alice schema:knows :bob .:bob schema:knows :carol .:carol schema:knows :bob .:carol schema:knows :alice .TurtleN-TriplesNote:We will see later other Turtle simplifications

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraNamespaces simplificationhttp://example.org/aliceex:bobhttp://example.org/carolhttp://example.org/bobhttp://schema.org/knowshttp://schema.org/knowshttp://schema.org/knowshttp://schema.org/knows:aliceex:bob:carol:bobschema:knowsschema:knowsschema:knowsschema:knows

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF is compositionalRDF graphs can be merged to obtain a bigger graphAutomatic data integrationschema:knowsschema:knowsschema:knows:aliceex:bob:carol:bobschema:knowsschema:birthPlace:carol schema:birthPlacedbr:Oviedo:bobgraph 1 graph 2

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF is compositionalRDF graphs can be merged to obtain a bigger graphAutomatic data integrationschema:birthPlaceschema:knowsschema:knowsschema:knows:aliceex:bob:carol schema:birthPlacedbr:Oviedo:bobschema:knowsgraph 1 + graph 2

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraTurtle syntaxSome simplificationsprefix declarations; when triples share the subject, when triples share subject and object:alice schema:birthPlace dbr:Oviedo ;schema:knows :bob .:alice schema:birthPlace dbr:Oviedo .:alice schema:knows :bob .:alice schema:knows :alice .:alice schema:knows :bob .:carol schema:knows :alice , :bob .

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraTurtle syntaxExercise: simplifyprefix : <http://example.org/>prefix schema: <http://schema.org/>prefix dbr: <http://dbpedia.org/resource>:alice schema:knows :bob .:bob schema:knows :carol .:carol schema:knows :bob .:carol schema:knows :alice .:bob schema:birthPlace dbr:Spain .:carol schema:birthPlace dbr:Spain .prefix ex: <http://example.org/>prefix schema: <http://schema.org/>prefix dbr: <http://dbpedia.org/resource>:alice schema:knows :bob , :carol.:bob schema:knows :carol ;schema:birthPlace dbr:Spain .:carol schema:knows :bob, :alice ;schema:birthPlace dbr:Spain .Try it: https://tinyurl.com/y9wbdycp

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF LiteralsObjects can also be literalsLiterals contain a lexical form and a datatypeTypical datatypes = XML Schema primitive datatypesIf not specified, a literal has datatype xsd:string:bobRobertschema:name1980-03-10schema:birthDatexsd:datexsd:string:bob schema:name "Robert" ;:bob schema:birthDate "1980-03-10"^^<xsd:date>.Turtle notation

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRemember...RDF is compositionalMerging previous dataschema:birthPlaceschema:knowsschema:knowsschema:knows:aliceex:bob:caroldbr:Spainschema:birthDate:bobRobert xsd:string1980-03-10 xsd:dateschema:nameschema:knowsprefix : <http://example.org/>prefix schema: <http://schema.org/>prefix dbr: <http://dbpedia.org/resource>:alice schema:knows :bob , :carol.:bob schema:knows :carol ;schema:birthPlace dbr:Spain;schema:name "Robert";schema:birthDate "1980-03-10"^^<xsd:date>.:carol schema:knows :bob, :alice ;schema:birthPlace dbr:Spain .schema:birthPlace

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraBlank nodesSubjects and objects can also be Blank nodes:carolschema:knows23:age"Carol knows someone whose age is 23":carol schema:knows _:x ._:x :age 23 .:carol schema:knows [ :age 23 ] .Turtle notation with local identifierTurtle notation with square bracketsx(schema:knows(:carol,x)  :age(x, 23)Mathematical meaning:

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraBlank nodesex:aliceex:carolschema:knowsschema:knowsschema:birthPlaceex:daveschema:birthPlace:age23 xsd:integerschema:knowsAlice knows someone whoknows DaveCarol knows someone whoseage is 23 that was born in thesame place as Dave:alice schema:knows [ schema:knows :dave ] .:carol schema:knows [ :age 23 ;schema:birthPlace _:p ] .:dave schema:birthPlace _:p .

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraLanguage tagged stringsString literals can be qualified by a language tagThey have datatype rdfs:langStringex:spain rdfs:label "Spain"@en .ex:spain rdfs:label "España"@es .ex:spainSpainrdfs:labelEspañardfs:labelesenTurtle notation

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF data modelschema:knowsschema:knowsschema:knowsex:aliceex:bobex:carol schema:birthPlacedbr:Spainschema:knowsschema:knowsschema:birthDateex:bobRobert xsd:string1980-03-10 xsd:dateschema:nameschema:birthPlaceschema:knowsex:daveschema:birthPlaceschema:age23 xsd:integerschema:knowsSpainrdfs:labelEspañardfs:labelesen3 types of nodesURIsBlank nodesLiteralsSubjects: URIs or Blank nodesObjects: URIs, Blank nodes or literalsPredicates always URIsschema:birthPlace

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labra...and that's all about the RDF data modelThe RDF Data model is very simple

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF ecosystemRDF SyntaxShared entities and RDF vocabulariesApplications of RDFInference and ontologiesQuery languagesRDF Validation

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF syntaxFirst syntax based on XML: RDF/XMLN-Triples (enumerates all triples separated by dots)Turtle (human readability)JSON-LD...other syntaxes...

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF/XML<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"xmlns="http://example.org/"xmlns:schema="http://schema.org/"><rdf:Description rdf:about="http://example.org/carol"><schema:knows><rdf:Description rdf:about="http://example.org/bob"><schema:knows rdf:resource="http://example.org/carol"/><schema:name>Robert</schema:name><schema:birthDate rdf:datatype="xsd:date">1980-03-10</schema:birthDate></rdf:Description></schema:knows><schema:knows><rdf:Description rdf:about="http://example.org/alice"><schema:knows rdf:resource="http://example.org/bob"/><schema:knows rdf:resource="http://example.org/carol"/></rdf:Description></schema:knows><schema:knows rdf:parseType="Resource"><age rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">23</age></schema:knows></rdf:Description></rdf:RDF>First syntax

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraN-Triples<http://example.org/carol> <http://schema.org/knows> <http://example.org/bob> .<http://example.org/carol> <http://schema.org/knows> <http://example.org/alice> .<http://example.org/carol> <http://schema.org/knows> _:x ._:x <http://example.org/age> "23"^^<http://www.w3.org/2001/XMLSchema#integer> .<http://example.org/alice> <http://schema.org/knows> <http://example.org/bob> .<http://example.org/alice> <http://schema.org/knows> <http://example.org/carol> .<http://example.org/bob> <http://schema.org/knows> <http://example.org/carol> .<http://example.org/bob> <http://schema.org/name> "Robert" .<http://example.org/bob> <http://schema.org/birthDate> "1980-03-10"^^<xsd:date> .For testing and easy parsing...just triples separated by dots

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraTurtleDesigned to be human-readableprefix : <http://example.org/>prefix schema: <http://schema.org/>:alice schema:knows :bob , :carol .:bob schema:knows :carol ;schema:name "Robert";schema:birthDate "1980-03-10"^^<xsd:date>.:carol schema:knows :bob, :alice ;schema:knows [ :age 23 ] .

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraJSON-LDJson for linked data{"@context" : {"knows" : { "@id" : "http://schema.org/knows", "@type" : "@id" },"age" : { "@id" : "http://example.org/age", "@type" : "http://www.w3.org/2001/XMLSchema#integer" },"name" : { "@id" : "http://schema.org/name" },"birthDate" : { "@id" : "http://schema.org/birthDate", "@type" : "xsd:date" },"@vocab" : "http://example.org/","schema" : "http://schema.org/"},"@graph" : [{ "@id" : "http://example.org/alice","knows" : [ "http://example.org/bob", "http://example.org/carol" ] },{ "@id" : "http://example.org/bob","birthDate" : "1980-03-10","knows" : "http://example.org/carol","name" : "Robert" },{ "@id" : "http://example.org/carol","knows" : [ "http://example.org/bob", "http://example.org/alice", "_:x" ] },{ "@id" : "_:x","http://example.org/age" : 23 }]}

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraOther Turtle simplificationsRDF type propertyNumbersCollections

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF type propertyThe rdf:type property declares the type of a resource@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.@prefix schema: <http://schema.org/> .e:alice rdf:type schema:Person .e:bob rdf:type schema:Person .@prefix schema: <http://schema.org/> .:alice a schema:Person .:bob a schema:Person .rdf:type can be simplified as a

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraConstantsNumbers and boolean values can be represented without quotesThey are parsed as XML Schema datatypesDatatype Shorthand example Lexical examplexsd:integer 3 "3"^^xsd:integerxsd:decimal -3.14 "true"^^xsd:decimalxsd:double 3.14e2 "true"^^xsd:doublexsd:boolean true "true"^^xsd:boolean

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraCollectionsOrdered listsrdf:firstrdf:restrdf:restrdf:restschema:name:m23:resultsNew York City Marathonrdf:nil:bobrdf:first :alice:dave:m23 schema:name "New York City Marathon ";:results ( :dave :alice :bob ) .:m23 schema:name "New York City Marathon ";:results _:1 ._:1 rdf:first :dave ;rdf:next _:2 ._:2 rdf:first :alice ;rdf:next _:3 ._:3 rdf:first :bob ;rdf:next rdf:nil .Internally, represented as linked listsrdf:first

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraShared entities and vocabulariesThe use of URIs instead of plain strings facilitates:Merging data from heterogeneous sourcesAvoid ambiguityChallenge: Agreeing on common entities and propertiesAppearance of some popular vocabularies:schema.org: Joint effort from Google, Yahoo, Microsoft, YandexLinked open vocabularies Project: http://lov.okfn.org/

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraSome popular vocabularies and namespacesAlias URL Name Some propertiesrdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#RDF type, subject,predicate,object,…rdfs: http://www.w3.org/2000/01/rdf-schema# RDF Schema domain, rangeClass, PropertysubClassOf,…owl: http://www.w3.org/2002/07/owl# OWLOntologíassameAs,intersectionOfunionOf, …dc: http://purl.org/dc/elements/1.1/ Dublin Core author, date,creator, …schema http://schema.org/ Schema.org name, knows, etc.skos: http://www.w3.org/2008/05/skos# SKOSSimple KnowledgeOrganization Systembroader,narrower,Service http://prefix.cc can be used to find the most popular prefix for some URI

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraApplications of RDFFirst applicationsRDF & HTML: RDFa, MicrodataRDF to represent knowledgeRDF as an internal databaseLinked data

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraFirst RDF applicationsSome initiatives proposed by W3CRSS 1.0 was proposed with an RDF/XML based syntaxOther XML based versions were availableEARL: Evaluation and Reporting LanguageRDF/XML adoption was not popular

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF & HTMLPossibilitiesOne resource for HTML and another for metadata in RDFRDFa: Use HTML attributes to encode RDF triplesMicrodata: New HTML5 attributes can encode metadataThe bookThe Spring byCervanteswas publishedlast Saturday.The bookThe Spring byCervanteswas published<time itemprop="datePublished"content="2014-05-04">last saturday</time>.RDFa Microdata

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF to represent knowledgeFreebase: developed by Metaweb (2005)Open, shared database of world's knowledgeAcquired by Google in 2010. It is the basis of Google knowledge graphDBpedia (http://dbpedia.org)Extracts knowledge from Wikipedia and converts it to RDFWikidata (http://wikidata.org/)Free knowledge base edited collaborativelyDeveloped by Wikimedia foundation

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF as an internal databaseSpecialized RDF databases (triplestores)RDF = very flexible, easy to adapt to domain changesSeveral big companies are using RDF internallyExample: BBC, Europeana

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF for Linked open dataPrinciples proposed by Tim Berners-Lee to publish data:1. Use URIs to denote things2. Use HTTP URIs so that people can look up those names3. When someone looks up a URI, provide useful information, using thestandards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things.

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF as the basis of Semantic WebRDF = lingua franca of Semantic WebSemantic web layer cakeURIUnicodeXML + Namespaces + XML SchemaProofRDF + RDF SchemaOntologiesLogicTrustFirst version proposed by Tim Berners Lee, year 2000http://www.w3.org/2000/Talks/1206-xml2k-tbl/slide10-0.html

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDF as the basis of Semantic WebRDF = lingua franca of Semantic WebSemantic web layer cake (revised)URIUnicodeXML/JSON/...RDFQuery:SPARQLRDFSOntologiesOWLTrustUnifying LogicRulesRIFProofValidationSHACLShEx

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDFS & inferences

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDFSOriginally RDF Schema (2000)Defines a vocabulary for common conceptsClasses: rdfs:Class, rdfs:Property, rdfs:LiteralProperties: rdfs:domain, rdfs:range, rdfs:subClassOf, ...

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraRDFSRDFS processors can infer new triplesRDFS defines several rules for inference:IF x rdf:type A AND A rdfs:subClassOf B THEN x rdf:type B:alice:Lecturerrdf:type:Personrdfs:subClassOfrdf:type

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraOWLWeb Ontology Language.First version (2004), OWL 2 (2009)Based on description logicsLanguage to describe classes, individuals, relationships

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraOWL example<> a owl:Ontology .:Man a owl:Class ;owl:equivalentClass [owl:intersectionOf (:Person[ a owl:Restriction ;owl:onProperty schema:gender ; owl:hasValue schema:Male] )] .:Woman a owl:Class ;owl:equivalentClass [owl:intersectionOf ( :Person[ a owl:Restriction ;owl:onProperty schema:gender ; owl:hasValue schema:Female] )] .[ a owl:AllDisjointClasses ; owl:members ( :Woman :Man ) ] .:Person owl:equivalentClass [ rdf:type owl:Class ;owl:unionOf ( :Woman :Man )] .:alice a :Woman ;schema:gender schema:Female .:bob a :Man .:alice a :Person .:bob a :Person .:bob schema:gender schema:Male .Instance dataInferred data

Jose Emilio Labra Gayo http://www.di.uniovi.es/~labraOWLOWL can been used to describe domain ontologiesDifferent kinds of ontologies:Upper level ontologies (SUMO, WordNet, ...)Domain specific (example: SNOMED)Tools to edit ontologies: Protégé editor

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