The Physics Department of the University of Cagliari and the Linkalab Group invited me to talk about the Semantic Web and Linked Data - this is simply an introduction to the technologies involved.

1. LINKING OPEN, BIG DATA USING
SEMANTIC WEB TECHNOLOGIES
AN INTRODUCTION
Dr. Ronald Ashri - Istos srl
http://www.istos.it

2. THE GOAL

3. connect and explore data
to discover hidden patterns
and create new information
new information enables us to
formulate better solutions
and identify new oportunities

7. the billion
dollar-o-gram

8. TOOLS
statistical analysis
network analysis
simulation
(evolutionary,
biologically inspired
systems)
symbolic manipulation

10. THE SEMANTIC WAY
Build Models
Calculate with knowledge
Exchange Information
Visualize - Analyze

11. BUILDING MODELS
AND CALCULATING

12. BUILDING MODELS
what things can be said to exist
what is reality?
bring structure into modeling

13. ontology is a description of knowledge about
a domain of interest
ὸντος = that is how it is

14. arbor porhyriana
Substance
immaterial
material
Body Spirit
animate inanimate
Living Mineral
sensitive insensitive
Animal Plant
rational irrational
Human Beast
234AD, Tyre (Lebanon)

15. knowledge on the web is modeled using
RDF, RDFs
and/or the Web Ontology Language - OWL

16. RDF
Resource Description Framework
directed labelled graph
capitalOf
Cagliari Sardegna
subject predicate object

17. URI
Uniform Resource Identifiers
a compact sequence of characters to identify an
abstract or physical resource
scheme:[//authority]path[?query][#fragment]
e.g. http://www.regione.sardegna.it/uri

18. RDF + URI
http://example.org/capitalOf
Cagliari Sardegna
http://www.comune.cagliari.it/uri http://www.regione.sardegna.it/uri

19. RDF + URI
eg:livesIn
Ronald Sicily
http://www.istos.it/ronald#me http://dbpedia/resource/Sicily
eg:worksFor
Ronald Istos
http://www.istos.it/ronald#me http://www.istos.it/uri
foaf:based_near
Istos Ispica
http://www.istos.it/uri http://dbpedia/resource/Ispica

20. RDF SCHEMA
RDF is a general way to describe structured
information
RDF Schema extends RDF to express general
information about a data set
Resources, Classes, Literals, Datatypes, Properties
range, domain, subClassOf, subPropertyOf

21. RDFS SERIALIZATIONS
N3, N-Triples, Turtle
Human readable, limited software support
RDF XML
takes advantage of tools to parse XML
RDFa - enables RDF to be embedded in HTML

22. OWL
Offers more expresivity
Classes (e.g. City, Region, Country)
Roles (e.g. containedWithin)
Individuals (e.g. Cagliari, Sardegna)

23. CALCULATING
Cagliari is a City deduction =>
Cagliari is
Cagliari is containedWithin Italy
containedWithin
Sardegna
Sardegna is a Region
Sardegna is
containedWithin Italy

24. Class(a:giraffe partial a:animal
restriction(a:eats allValuesFrom (a:leaf)))
Class(a:leaf partial restriction(a:part_of someValuesFrom (a:tree)))
Class(a:tree partial a:plant)
DisjointClasses(unionOf(restriction(a:part_of someValuesFrom (a:animal)) a:animal)
unionOf(a:plant restriction(a:part_of someValuesFrom (a:plant))))
Class(a:vegetarian complete intersectionOf(
restriction(a:eats allValuesFrom (complementOf(restriction(a:part_of
someValuesFrom (a:animal)))))
restriction(a:eats allValuesFrom (complementOf(a:animal))) a:animal))
• Giraffes only eat leaves
• Leaves are parts of trees, which are plants
• Plants and parts of plants are disjoint from animals and parts of
animals
• Vegetarians only eat things which are not animals or parts of
animals

25. Figure 2: Agent-Based Market Model

26. (a) Dependency: α sells (b) Comp-Sell: α and β (c) Comp-Buy: The goal (d) Coll: α sells to β
goods to B are competing in α’s RoI of α is the same that the and β sells to α
goal of β
Figure 3: Key Relationship Patterns
on the buyer. We specify a dependency relationships in terms of
y y
goals in the following way: Dep(q(gα ), a(gβ ))RoIβ ⊆V Eα , where
y is the product β is selling to α (i.e. α wants to achieve the goal
of having y), and β’s region of influence is withing α’s viewable
environment as for trade relationships.
4.3 Competition

27. OWL - XML-based syntax
suitable for machines and use in web documents
OWL - abstract syntax
easier to read and write
closer to description logics

28. balance between expressivity and efficient reasoning
complex language constructs for respresenting
implicit knowledge yield high computational
complexities or even undecidability

29. OWL Lite
decidable
less expressive
ExpTime

30. OWL DL
contains OWL Lite
decidable
supported by software tools
NExpTime

31. OWL Full
very expressive
undecidable

32. THE PROCESS
Build an ontology or
vocabulary
State facts about
domain
Reason about
ontologies and facts

33. EXCHANGING
INFORMATION

34. WWW 0.1
the original web was
thought of with
ontological
information at its
heart
http://www.w3.org/History/1989/proposal.html

35. ??
??

36. THE PROBLEM
http://www.w3.org/Talks/WWW94Tim/

37. THE SEMANTIC WEB

38. SPARQL
Protocol and RDF Query Language
Graph pattern matching
Uses RDF triples but they may be variables
The reply is the RDF graph equivalent to the
subgraph described

39. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?email
WHERE {
?person a foaf:Person.
?person foaf:name ?name.
?person foaf:mbox ?email.
}
endpoint: world-wide web
names and e-mails of every person in the world!

40. EXCHANGE MORE
INFORMATION
THE LINKED DATA EFFORT

41. the semantic web provided tools but
not enough method - the linked data
effort tries to rectify this

42. 1. Use URIs as names for things
2. Use HTTP URIs so that people can look things up
3. Provide useful info using standards (Sparql)
4. Include links to other URIs

43. USE URIS
Basic - if you are not using URIs it is not Semantic
Web

44. USE HTTP URIS
stop inventing your own schemas
HTTP works - browsers know it - let us take
advantage of it

45. HELP OTHERS
when people look up HTTP URIs make the data
available and/or provide Sparql support

46. Available on the web (whatever format), but with an open
licence
Available as machine-readable structured data (e.g. excel
instead of image scan of a table)
as (2) plus non-proprietary format (e.g. CSV instead of
excel)
All the above plus, Use open standards from W3C (RDF
and SPARQL) to identify things, so that people can point at your
stuff
All the above, plus: Link your data to other people’s
data to provide context

48. datasets

49. UMBEL - Reference concept ontology
28000 scaffold concepts

50. services

55. REASON, VISUALIZE

59. the fear index

61. LOOKING AHEAD
Technology and tools
are getting there
Data needs to remain
open
Spread the word -
Annotate!

62. QUESTIONS
ronald@istos.it
@ronald_istos