The Web of the Future: Introduction to the Semantic Web - Bulgaria PHP 2019

What if we could evolve our web of individual documents and data to a web of interlinked knowledge, a web where machines can automatically combine data from multiple sources and draw conclusions from it? The Semantic Web technologies from W3C enable us to make sense of the data wilderness on the web and unlock the full potential of the data treasures hidden in it.

In this talk, we will see how RDF enables us to formally describe the meaning of data and how such data can be queried with SPARQL. We will look at how OWL lets us make more expressive statements about the world, so that a computer can logically reason about it and infer new information. We will demonstrate these technologies by showing how they can be used to query seemingly incompatible data sets as if they were one and letting a computer draw logical (and perhaps surprising) conclusions for us.

Contains: ‘retro’ technology, linked data, fundamental properties of the web, and Donald Trump’s opinion on PHP frameworks.

Transcript

1. The Web of the Future:
   Introduction to the Semantic Web
   @arnoutboks
   Arnout Boks
   #bgphp19
   09-11-2019
   

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2. @arnoutboks #bgphp19
   What this talk is NOT about…
   

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3. @arnoutboks #bgphp19
   Finding info on the web
   An example
   

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4. @arnoutboks #bgphp19
   “Web 1.0”
   

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5. @arnoutboks #bgphp19
   “Web 1.0”
   

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6. @arnoutboks #bgphp19
   “Web 1.0”
   

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7. @arnoutboks #bgphp19
   Web 1.0
   Web of Documents
   for human consumption
   

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8. @arnoutboks #bgphp19
   “Web 2.0”
   Feed of events
   • iCalendar or vCalendar?
   • Different types of events?
   

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9. @arnoutboks #bgphp19
   “Web 2.0”
   Weather forecast API
   • XML or JSON?
   • Which fields and properties?
   • Which units?
   

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10. @arnoutboks #bgphp19
    Web 2.0
    Web of (individual) API’s
    for consumption by
    specialized software
    

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11. @arnoutboks #bgphp19
    Semantic web
    • Question to agent (e.g. Siri, Google Assistant)
    • Agent searches across different sources
    • Agent combines data
    • Agent answers question
    

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12. @arnoutboks #bgphp19
    Semantic Web
    (“Web 3.0”?)
    Web of Linked Data
    for consumption by
    intelligent agents/PA’s
    

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13. @arnoutboks #bgphp19
    Revolutionary?
    Term coined by Tim Berners-Lee in 2001
    

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14. @arnoutboks #bgphp19
    Revolutionary?
    Based on W3C-standards
    • RDF (1998)
    • RDFS (1998)
    • SPARQL (2008)
    • OWL (2004)
    • …
    

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15. @arnoutboks #bgphp19
    RDF
    Cornerstone of the Semantic Web
    Resource Description Framework
    Cornerstone of the Semantic Web
    

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16. @arnoutboks #bgphp19
    Records statements
    about things
    

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17. @arnoutboks #bgphp19
    RDF allows
    reading, merging, relaying
    and inferring statements
    without fully understanding them
    

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18. @arnoutboks #bgphp19
    RDF (triples)
    Subject Predicate Object
    

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19. @arnoutboks #bgphp19
    RDF (triples)
    Subject Predicate Object
    Arnout worksAt Moxio
    

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20. @arnoutboks #bgphp19
    RDF (triples)
    Subject Predicate Object
    Arnout worksAt Moxio
    Arnout twitterHandle “@arnoutboks”
    Arnout livesIn Delft
    Delft cityIn The Netherlands
    Moxio basedIn Delft
    

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21. @arnoutboks #bgphp19
    RDF (graph)
    Arnout Moxio
    Delft
    @arnoutboks
    worksAt
    basedIn
    The
    Netherlands
    Subject Predicate Object
    Arnout worksAt Moxio
    Arnout twitterHandle “@arnoutboks”
    Arnout livesIn Delft
    Delft cityIn The Netherlands
    Moxio basedIn Delft
    

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22. @arnoutboks #bgphp19
    Merging RDF (triples)
    Subject Predicate Object
    Arnout worksAt Moxio
    Arnout twitterHandle “@arnoutboks”
    Arnout livesIn Delft
    Delft cityIn The Netherlands
    Moxio basedIn Delft
    Subject Predicate Object
    The Netherlands hasCapital Amsterdam
    The Netherlands population “17.000.000”
    

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23. @arnoutboks #bgphp19
    Merging RDF (triples)
    Subject Predicate Object
    Arnout worksAt Moxio
    Arnout twitterHandle “@arnoutboks”
    Arnout livesIn Delft
    Delft cityIn The Netherlands
    Moxio basedIn Delft
    The Netherlands hasCapital Amsterdam
    The Netherlands population “17.000.000”
    

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24. @arnoutboks #bgphp19
    Merging RDF (graph)
    Arnout Moxio
    Delft
    @arnoutboks
    worksAt
    basedIn
    The
    Netherlands
    Amsterdam
    hasCapital
    17.000.000
    population
    

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25. @arnoutboks #bgphp19
    Serializing RDF: Turtle
    @prefix : .
    @prefix rdf: ns#> .
    @prefix xsd: .
    @base .
    :Arnout :livesIn :Delft ;
    :worksAt :Moxio ;
    :twitterHandle "@arnoutboks"^^xsd:string .
    :Delft :cityIn :The_Netherlands .
    :Moxio :basedIn :Delft .
    

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26. @arnoutboks #bgphp19
    Serializing RDF: RDF/XML
    
    >
    rdf:about="http://www.example.com/#Arnout">
    rdf:datatype="http://www.w3.org/2001/XMLSchema#string">@a
    rnoutboks
    rdf:resource="http://www.example.com/#Moxio"/>
    rdf:resource="http://www.example.com/#Delft"/>
    
    
    
    

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27. @arnoutboks #bgphp19
    Serializing RDF: JSON-LD
    [ {
    "@id" : "http://www.example.com/#Arnout",
    "http://www.example.com/#livesIn" : [ {
    "@id" : "http://www.example.com/#Delft"
    } ],
    "http://www.example.com/#twitterHandle" : [ {
    "@value" : "@arnoutboks"
    } ],
    "http://www.example.com/#worksAt" : [ {
    "@id" : "http://www.example.com/#Moxio"
    } ]
    }, ... ]
    

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28. @arnoutboks #bgphp19
    RDF is an abstract
    data model
    with different serialization formats
    

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29. @arnoutboks #bgphp19
    Identity
    Because there are multiple things named “Amsterdam”
    

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30. @arnoutboks #bgphp19
    Identity
    Subject Predicate Object
    Amsterdam numberOfGuns “42”
    Amsterdam status Wrecked
    National Maritime Museum (“Scheepvaartmuseum”)
    

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31. @arnoutboks #bgphp19
    Identity
    Subject Predicate Object
    Amsterdam numberOfGuns “42”
    Amsterdam status Wrecked
    Subject Predicate Object
    The Netherlands hasCapital Amsterdam
    The Netherlands population “17.000.000”
    National Maritime Museum (“Scheepvaartmuseum”)
    Lonely Planet
    

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32. @arnoutboks #bgphp19
    Identity
    The
    Netherlands
    Amsterdam
    hasCapital
    17.000.000
    population
    42
    Wrecked
    

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33. @arnoutboks #bgphp19
    URI’s for namespacing
    National Maritime Museum (“Scheepvaartmuseum”)
    https://www.hetscheepvaartmuseum.nl/ships/Amsterdam
    https://www.hetscheepvaartmuseum.nl/ships/numberOfGuns
    Lonely Planet
    https://www.lonelyplanet.com/Amsterdam
    https://www.lonelyplanet.com/hasCapital
    

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34. @arnoutboks #bgphp19
    Prefixes & QNames
    lonelyplanet:Amsterdam
    ===
    https://www.lonelyplanet.com/Amsterdam
    QName
    URI
    local name
    local name
    namespace
    prefix
    

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35. @arnoutboks #bgphp19
    Prefixes & QNames
    National Maritime Museum (“Scheepvaartmuseum”)
    nmm:Amsterdam
    nmm:numberOfGuns
    Lonely Planet
    lonelyplanet:Amsterdam
    lonelyplanet:hasCapital
    

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36. @arnoutboks #bgphp19
    Three fundamental laws
    of the (Semantic) Web
    

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37. @arnoutboks #bgphp19
    Different name, different concept?
    lonelyplanet-en:Brussels
    lonelyplanet-nl:Brussel
    lonelyplanet-bg:Брюксел
    lonelyplanet-zh:布魯塞爾
    

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38. @arnoutboks #bgphp19
    Different name, different concept?
    mi6:007
    mi6:JamesBond
    

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39. @arnoutboks #bgphp19
    Nonunique Naming Assumption
    Different names do not
    imply different concepts
    

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40. @arnoutboks #bgphp19
    Truth & authority
    Subject Predicate Object
    whitehouse:Obama nsa:tapped whitehouse:Trump
    Donald Trump
    

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41. @arnoutboks #bgphp19
    Truth & authority
    Subject Predicate Object
    php-fig:CakePHP fw:isBetterThan php-fig:Symfony
    Donald Trump
    

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42. @arnoutboks #bgphp19
    The AAA Slogan
    “[On the web] Anyone can say
    Anything about Any topic”
    

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43. @arnoutboks #bgphp19
    (this slide intentionally left blank)
    

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44. @arnoutboks #bgphp19
    Absence of information
    Subject Predicate Object
    whitehouse:Trump fw:knows php-fig:Symfony
    whitehouse:Trump fw:knows php-fig:CakePHP
    whitehouse:Trump fw:knows php-fig:CodeIgniter
    

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45. @arnoutboks #bgphp19
    Open World Assumption
    We never have all information
    

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46. @arnoutboks #bgphp19
    SPARQL
    Query language for Semantic Web data
    

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47. @arnoutboks #bgphp19
    Triple Store
    Database for RDF triples
    

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48. @arnoutboks #bgphp19
    SPARQL
    SELECT ?employee ?company
    WHERE {
    ?employee :worksAt ?company .
    ?company :basedIn :Delft .
    }
    

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49. @arnoutboks #bgphp19
    SPARQL
    SELECT ?employee ?company
    WHERE {
    ?employee :worksAt ?company .
    ?company :basedIn :Delft .
    }
    ?employee ?company
    :Arnout :Moxio
    

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50. @arnoutboks #bgphp19
    SPARQL
    SELECT ?employee ?company ?city
    WHERE {
    ?employee :worksAt ?company .
    ?company :basedIn ?city .
    ?employee :livesIn ?city .
    }
    ?employee ?company ?city
    :Arnout :Moxio :Delft
    

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51. @arnoutboks #bgphp19
    Online SPARQL endpoints
    http://dbpedia.org/sparql
    

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52. @arnoutboks #bgphp19
    Online SPARQL endpoints
    

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53. @arnoutboks #bgphp19
    Online SPARQL endpoints
    PREFIX dbo:
    PREFIX dbr:
    SELECT ?song ?runtime
    WHERE {
    ?song dbo:artist dbr:The_Beatles .
    ?song dbo:runtime ?runtime .
    ?song rdf:type dbo:Song .
    } ORDER BY DESC (?runtime)
    

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54. @arnoutboks #bgphp19
    Online SPARQL endpoints
    

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55. @arnoutboks #bgphp19
    Online SPARQL endpoints
    PREFIX dbo:
    PREFIX dbr:
    SELECT ?ancestor
    WHERE {
    dbr:Willem-Alexander_of_the_Netherlands
    dbo:parent+ ?ancestor .
    }
    

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56. @arnoutboks #bgphp19
    RDF Schema
    Schema language for Semantic Web data
    

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57. @arnoutboks #bgphp19
    RDF Schema (RDFS)
    Describes the structure of RDF-data… in RDF
    • Classes
    • Properties
    • Domain and range of properties
    • Inheritance of classes
    • ‘Inheritance’ of properties
    

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58. @arnoutboks #bgphp19
    RDF Schema (RDFS)
    Subject Predicate Object
    :DonaldTrump :isFatherOf :IvankaTrump
    

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59. @arnoutboks #bgphp19
    RDF Schema (RDFS)
    Subject Predicate Object
    :DonaldTrump :isFatherOf :IvankaTrump
    :isFatherOf rdfs:range :Person
    :isFatherOf rdfs:domain :Father
    :Father rdfs:subclassOf :Parent
    :Parent rdfs:subclassOf :Person
    :isFatherOf rdfs:subpropertyOf :isParentOf
    

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60. @arnoutboks #bgphp19
    RDF Schema & Inference
    Subject Predicate Object
    :DonaldTrump :isFatherOf :IvankaTrump
    :isFatherOf rdfs:range :Person
    :isFatherOf rdfs:domain :Father
    :Father rdfs:subclassOf :Parent
    :Parent rdfs:subclassOf :Person
    :isFatherOf rdfs:subpropertyOf :isParentOf
    :IvankaTrump rdf:type :Person
    :DonaldTrump rdf:type :Father
    :DonaldTrump rdf:type :Parent
    :DonaldTrump rdf:type :Person
    :DonaldTrump :isParentOf :IvankaTrump
    

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61. @arnoutboks #bgphp19
    Inference
    Reasoner
    (asserted) triples
    inferred/virtual triples
    

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62. @arnoutboks #bgphp19
    Inference
    Reasoner
    (asserted) triples
    inferred/virtual triples
    

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63. @arnoutboks #bgphp19
    SPARQL & Inference
    SELECT ?person
    WHERE { ?person rdf:type :Person . }
    ?person
    :IvankaTrump
    :DonaldTrump
    

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64. @arnoutboks #bgphp19
    Combining data using inference
    Subject Predicate Object
    a:DonaldTrump rdf:type a:Person
    Datasource A
    Subject Predicate Object
    b:MelaniaTrump rdf:type b:Human
    Datasource B
    

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65. @arnoutboks #bgphp19
    Combining data using inference
    Subject Predicate Object
    a:DonaldTrump rdf:type a:Person
    Datasource A
    Subject Predicate Object
    b:MelaniaTrump rdf:type b:Human
    Datasource B
    Subject Predicate Object
    a:Person rdfs:subclassOf b:Human
    b:Human rdfs:subclassOf a:Person
    Mapping rules
    

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66. @arnoutboks #bgphp19
    Combining data using inference
    Subject Predicate Object
    a:DonaldTrump rdf:type a:Person
    b:MelaniaTrump rdf:type b:Human
    a:Person rdfs:subclassOf b:Human
    b:Human rdfs:subclassOf a:Person
    a:DonaldTrump rdf:type b:Human
    b:MelaniaTrump rdf:type a:Person
    

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67. @arnoutboks #bgphp19
    Query different sources
    as if they were one
    

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68. @arnoutboks #bgphp19
    RDF Schema vs. JSON/XML Schema
    Subject Predicate Object
    mi6:JamesBond rdf:type mi6:SecretAgent
    mi6:JamesBond nmm:numberOfGuns “1”
    MI6 files
    

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69. @arnoutboks #bgphp19
    RDF Schema vs. JSON/XML Schema
    Subject Predicate Object
    mi6:JamesBond rdf:type mi6:SecretAgent
    mi6:JamesBond nmm:numberOfGuns “1”
    MI6 files
    

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70. @arnoutboks #bgphp19
    RDF Schema vs. JSON/XML Schema
    Subject Predicate Object
    mi6:JamesBond rdf:type mi6:SecretAgent
    mi6:JamesBond nmm:numberOfGuns “1”
    MI6 files
    Subject Predicate Object
    nmm:numberOfGuns rdf:domain nmm:Ship
    National Maritime Museum (“Scheepvaartmuseum”)
    

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71. @arnoutboks #bgphp19
    RDF Schema vs. JSON/XML Schema
    Subject Predicate Object
    mi6:JamesBond rdf:type mi6:SecretAgent
    mi6:JamesBond nmm:numberOfGuns “1”
    nmm:numberOfGuns rdf:domain nmm:Ship
    mi6:JamesBond rdf:type nmm:Ship
    

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72. @arnoutboks #bgphp19
    RDF Schema vs. JSON/XML Schema
    

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73. @arnoutboks #bgphp19
    RDF Schema will never
    consider data to be invalid
    

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74. @arnoutboks #bgphp19
    Web Ontology Language (OWL)
    Even smarter inferencing
    Web Ontology Language (OWL)
    Even smarter inferencing
    

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75. @arnoutboks #bgphp19
    OWL
    OWL ≈ RDFS++
    

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76. @arnoutboks #bgphp19
    OWL
    Power comes at a price…
    

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77. @arnoutboks #bgphp19
    OWL: Inverse properties
    Subject Predicate Object
    :DonaldTrump :isParentOf :IvankaTrump
    :isParentOf owl:inverseOf :isChildOf
    :IvankaTrump :isChildOf :DonaldTrump
    

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78. @arnoutboks #bgphp19
    OWL: Symmetric properties
    Subject Predicate Object
    :DonaldTrump :isMarriedTo :MelaniaTrump
    :isMarriedTo rdf:type owl:SymmetricProperty
    :MelaniaTrump :isMarriedTo :DonaldTrump
    

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79. @arnoutboks #bgphp19
    OWL: Equality
    Subject Predicate Object
    :DonaldTrump :isMarriedTo :MelaniaTrump
    :DonaldTrump owl:sameAs :TheDon
    :TheDon :isMarriedTo :MelaniaTrump
    

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80. @arnoutboks #bgphp19
    OWL: Functional properties
    Subject Predicate Object
    :IvankaTrump :hasFather :DonaldTrump
    :IvankaTrump :hasFather :TheDon
    :hasFather rdf:type owl:FunctionalProperty
    :TheDon owl:sameAs :DonaldTrump
    

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81. @arnoutboks #bgphp19
    Inconsistency
    Subject Predicate Object
    :IvankaTrump :hasFather :DonaldTrump
    :IvankaTrump :hasFather :TheDon
    :hasFather rdf:type owl:FunctionalProperty
    :TheDon owl:differentFrom :DonaldTrump
    

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82. @arnoutboks #bgphp19
    Inconsistency
    

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83. @arnoutboks #bgphp19
    Inconsistency
    

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84. @arnoutboks #bgphp19
    It’s okay to be inconsistent…
    (remember the AAA slogan)
    

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85. @arnoutboks #bgphp19
    It’s okay to be inconsistent…
    (remember the AAA slogan)
    …but the reasoner won’t
    help you anymore
    

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86. @arnoutboks #bgphp19
    Self-test
    Subject Predicate Object
    :George :hasChild :Michelle
    :George :hasChild :James
    How many children does George have?
    

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87. @arnoutboks #bgphp19
    Further steps
    Get going with the Semantic Web
    

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88. @arnoutboks #bgphp19
    Leveraging the Semantic Web
    Network effect
    

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89. @arnoutboks #bgphp19
    Leveraging the Semantic Web
    Only useful when multiple parties
    speak the same ‘language’
    

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90. @arnoutboks #bgphp19
    Align with existing
    vocabularies
    

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91. @arnoutboks #bgphp19
    Leveraging the Semantic Web
    Mapping between vocabularies:
    • rdfs:subclassOf
    • rdfs:subpropertyOf
    • owl:inverseOf
    • owl:sameAs
    

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92. @arnoutboks #bgphp19
    Existing vocabularies
    • Dublin Core
    • Metadata about publications and authors
    • Friend of a Friend
    • People, connections, social networks
    • GoodRelations
    • Products, prices, eCommerce
    • CB-NL
    • Construction, infrastructure, spatial planning
    • QUDT
    • Quantities, units, dimensions, conversions
    

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93. @arnoutboks #bgphp19
    Resources
    • Apache Jena (includes Fuseki triple store)
    • Semantic web framework/tools (written in Java)
    • easyrdf/easyrdf
    • RDF parser/writer for PHP
    • semsol/arc2
    • PHP RDF library and MySQL-based triple store
    • FaCT++, HermiT & Pellet
    • Open source OWL reasoners
    • Protégé
    • RDF/OWL IDE with various reasoner plugins
    

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94. @arnoutboks #bgphp19
    Resources
    

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95. @arnoutboks #bgphp19
    Resources
    • https://www.w3.org/2013/data/
    • https://www.w3.org/2001/sw/wiki/
    • https://www.w3.org/TR/rdf11-primer/
    • https://www.w3.org/TR/owl2-primer/
    • https://www.w3.org/TR/sparql11-query/
    • http://wiki.dbpedia.org/OnlineAccess
    • https://www.data.gov/
    • http://lod-cloud.net/
    

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96. @arnoutboks #bgphp19
    Feedback & Questions
    Please leave your feedback on joind.in:
    https://joind.in/talk/de222
    @arnoutboks
    https://aboks.github.io
    Arnout Boks
    

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97. @arnoutboks #bgphp19
    Image Credits
    • https://www.flickr.com/photos/lex-photographic/32521124574
    • https://www.flickr.com/photos/rwoan/34676675925
    • https://www.flickr.com/photos/littlehuw/15236543728
    • https://www.flickr.com/photos/crdominguez/422517106
    • https://www.flickr.com/photos/pamwood707/5646757752
    • https://www.flickr.com/photos/blair25/3240686470
    • https://www.flickr.com/photos/tylerbeaulawrence/15167523690
    • https://www.flickr.com/photos/23975018@N04/3675503072
    • https://pixabay.com/nl/nuance-stalen-kleur-pantone-1074766/
    • https://www.flickr.com/photos/borkurdotnet/9682277597
    

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