Semantic Web Basics

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Semantic Web Basics

• Dominic DiFranzo
• PhD Student/Research Assistant
• Rensselaer Polytechnic Institute
• Tetherless World Constellation

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http//tw.rpi.edu/portal/Mashathon
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Interwebs?

• Internet graph of computers connected to one
  another
• Web graph of documents hyper-linked to one
  another
• Semantic web graph of concepts/ideas/data
  linked together by named relations.

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RDF

• Triple Subject Predicate Object
• Use URI for universal naming
• New York has the postal abbreviation NY
• lturnx-statesNew20Yorkgt
  lthttp//purl.org/dc/terms/alternativegt "NY" .

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Linked Open Data
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serialize in many ways
ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-
rdf-syntax-ns" xmlnsdcterms"http//purl.org/d
c/terms/"gt ltrdfDescription
rdfabout"urnx-statesNew20York"gt
ltdctermsalternativegtNYlt/dctermsalternativegt
lt/rdfDescriptiongt lt/rdfRDFgt
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Linking

• I found a new dataset and it has the following
  triple
• lthttp//dbpedia.org/page/New_Yorkgt
  lthttp//dbpedia.org/ontology/Place/otherNamegt
  The Empire State .

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owlsameAS

• lturnx-statesNew20Yorkgt lthttp//www.w3.org/2002/
  07/owlsameAsgt lthttp//dbpedia.org/page/New_Yorkgt
  .

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Semantic Mashup Workflow

• Take data (CSV, XSL)
• Convert it to RDF
• Load in triple store
• Query with Sparql
• Visualize results using standard off-the-shelf
  visualization tools (Google viz, Exhibit, etc)

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(No Transcript)
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Conversion to RDF
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Sparql

• SPARQL is a query language for the Semantic Web.

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Sparql
SELECT ?node ?title WHERE  ?node
lthttp//purl.org/dc/elements/1.1/titlegt ?title .
LIMIT 1
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Long!
SELECT ?node ?name WHERE  ?node
lthttp//xmlns.com/foaf/0.1/givennamegt ?name .
 ?node lthttp//www.w3.org/1999/02/22-rdf-syntax-ns
typegt lthttp//xmlns.com/foaf/0.1/Persongt .
LIMIT 10
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Prefix
PREFIX foaf lthttp//xmlns.com/foaf/0.1/gt PREFIX
rdf lthttp//www.w3.org/1999/02/22-rdf-syntax-nsgt
SELECT ?node ?name WHERE  ?node
foafgivenname ?name .  ?node rdftype
foafPerson . LIMIT 10
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Shortcuts
PREFIX foaf lthttp//xmlns.com/foaf/0.1/gt
PREFIX rdf lthttp//www.w3.org/1999/02/22-rdf-synt
ax-nsgt SELECT ?node ?name WHERE  ?node
foafgivenname ?name  rdftype
foafPerson . LIMIT 10
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Graphs
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Named Graph
PREFIX dc lthttp//purl.org/dc/elements/1.1/gt
SELECT ?graph ?node ?title WHERE
GRAPH ?graph  ?node dctitle ?title .
LIMIT 3
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Named Graph
PREFIX dc lthttp//purl.org/dc/elements/1.1/gt
SELECT  ?node8 ?desc8 ?node401 ?desc401 WHERE
GRAPH lthttp//data-gov.tw.rpi.edu/vocab/Dataset_4
01gt  ?node401 dcdescription ?desc401 .
GRAPH lthttp//data-gov.tw.rpi.edu/vocab/Datas
et_8gt  ?node8 dcdescription ?desc8 .
LIMIT 3
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Union
PREFIX dc lthttp//purl.org/dc/elements/1.1/gt
SELECT  ?node8 ?desc8 ?node401 ?desc401 WHERE
GRAPH lthttp//data-gov.tw.rpi.edu/vocab/Da
taset_401gt  ?node401 dcdescription ?desc40
1 . UNION GRAPH
lthttp//data-gov.tw.rpi.edu/vocab/Dataset_8gt
 ?node8 dcdescription ?desc8 .
LIMIT 3
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Optional
PREFIX foaf lthttp//xmlns.com/foaf/0.1/gt
SELECT  ?node ?name ?givenname WHERE
 ?node foafname ?name . OPTIONAL
 ?node foafgivenname ?givenname .
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Filter
PREFIX foaf lthttp//xmlns.com/foaf/0.1/gt
SELECT  ?node ?name ?givenname WHERE
 ?node foafname ?name .  ?node
foafgivenname ?givenname . FILTER
regex(?name, "Biden") .
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Try some on your own
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Questions?