The ‘K’ in ‘Semantic Web’ stands for Knowledge

February 1st, 2017

Wouter Beek (w.g.j.beek@vu.nl)

How much structured data is there?

  • WebDataCommons: 44.2B statements from Microdata, Embedded JSON-LD, RDFa and Microformats (5.6M PLDs).
  • LOD Laundromat: 38,6B statements from data documents (650K documents).
  • ~600 SPARQL endpoints
  • We know there is much more out there.

lodlaundromat.org



Beek & Rietveld & Bazoobandi & Wielemaker & Schlobach “LOD laundromat: A Uniform Way of Publishing Other People’s Dirty Data” ISWC, 2014.
Best Linked Data Application Award 2015.
3rd prize, European Linkd Data Application Award.

Reproducing “Linked Data Best Practices” (Schmachtenberg 2014)

Original LOD Lab
Prefix #datasets %datasets Prefix #documents %documents
rdf 996 98.22% rdf 639,575 98.40%
rdfs 736 72.58% time 443,222 68.19%
foaf 701 69.13% cube 155,460 23.92%
dcterm 568 56.01% sdmxdim 154,940 23.84%
owl 370 36.49% worldbank 147,362 22.67%

Rietveld & Beek & Schlobach, “LOD Lab: Experiments at LOD Scale”, International Semantic Web Conference, 2015 (best paper award).

geopolitics:hasBorderWidth

skos:exactMatch

foaf:knows

Graph A:

abox:store tbox:sells abox:tent .
abox:tent tbox:costs "¥150,000" .
abox:tent rdf:type abox:Product .


Graph B:

fy:aHup pe:ko9sap_ fy:jufn12 .
fy:jufn12 pe:oao9_ "Ufou" .
fy:jufn12 rdf:type fyufnt:tmffqt .

Information Theory (compression)

compress(SEMANTICS) + compress(NAMES)

- compress(SEMANTICS + NAMES)

= mutual information

De Rooij & Beek & Bloem & Schlobach & Van Harmelen, ‘Are Names Meaningful? Quantifying Social Meaning on the Semantic Web’ in ISWC, 2016.

How generalizable is SW research?

ISWC 2014 Research Track:

  • 17 datasets overall; avg. 2 per per paper
  • Data was cleaned locally and deleted afterwards

Assumptions of traditional KR approaches:

  • Quantity assumption
  • Accessibility assumption
  • Quality assumption
  • Context-independence assumption
  • Declarativeness assumption
  • Consistency assumption
  • Stability assumption

Query the LOD Cloud with Frank

https://github.com/LOD-Laundromat/Frank

Beek & Rietveld. “Frank: The LOD Cloud at your Fingertips” ESWC, 2015.

Thank you!

WWW: wouterbeek.com

Mail: w.g.j.beek@vu.nl