With this slide set I presented my position paper at the 2nd Workshop on Trust and Privacy on the Social and Semantic Web (SPOT) at EWC 2010

1. Towards a
Data-Centric Notion of Trust
in the Semantic Web
(A Position Statement)
Olaf Hartig
Database and Information Systems Research Group
Humboldt-Universität zu Berlin

2. Existing
Research
on Trust in the
(Semantic) Web
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 2

3. Existing Research on Trust
Trust( )=?
Focus on active entities
(e.g. persons, agents, peers)
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 3

4. Existing Research on Trust
Trust( )=?
What does it mean
to trust an active entity?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 4

5. Existing Research on Trust
Trust( )=?
● J.B. Barney and M.H. Hansen, 1994: Trust “is the mutual
confidence that one's vulnerability will not be exploited.”
What does it mean
to trust an active entity?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 5

6. Existing Research on Trust
Trust( )=?
● J.B. Barney and M.H. Hansen, 1994: Trust “is the mutual
confidence that one's vulnerability will not be exploited.”
● L. Mui, M. Mohtashemi and A. Halberstadt, 2002: Trust is
What does it mean
the “subjective expectation an agent has about another's
to trust an active entity?
future behavior based on the history of their encounters.”
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 6

7. Existing Research on Trust
Trust ( )=?
● J.B. Barney and M.H. Hansen, 1994: Trust “is the mutual
confidence that one's vulnerability will not be exploited.”
● L. Mui, M. Mohtashemi and A. Halberstadt, 2002: Trust is
What does it mean
the “subjective expectation an agent has about another's
to trust an active entity?
future behavior based on the history of their encounters.”
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 7

8. Existing Research on Trust
Trust ( )=?
● J.B. Barney and M.H. Hansen, 1994: Trust “is the mutual
confidence that one's vulnerability will not be exploited.”
● L. Mui, M. Mohtashemi and A. Halberstadt, 2002: Trust is
What does it mean
the “subjective expectation an agent has about another's
to trust an active entity?
future behavior based on the history of their encounters.”
● T. Grandison and M. Sloman, 2000: Trust is “the firm belief
in the competence of an entity to act dependably, securely,
and reliably within a specified context.”
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 8

9. Existing Research on Trust
Trust ( )=?
● J.B. Barney and M.H. Hansen, 1994: Trust “is the mutual
confidence that one's vulnerability will not be exploited.”
● L. Mui, M. Mohtashemi and A. Halberstadt, 2002: Trust is
What does it mean
the “subjective expectation an agent has about another's
to trust an active entity?
future behavior based on the history of their encounters.”
● T. Grandison and M. Sloman, 2000: Trust is “the firm belief
in the competence of an entity to act dependably, securely,
and reliably within a specified context.”
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 9

10. Existing Research on Trust
Trust ( )=?
How do we represent trust?
● Binary models (e.g. Golbeck and Hendler, 2004)
● Discrete models (e.g. Golbeck et al., 2003)
e.g. highly trusted, moderately trusted, …
● Continuous models (Brondsema and Schamp, 2006)
e.g. 0 … 1
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 10

11. Existing Research on Trust
Trust ( )=?
How do we calculate trust?
● Reputation based models
● Network based models (Web of trust)
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 11

12. Existing Research on Trust
Trust ( )=?
How do we calculate trust?
e Reputation based models
high
oderat
●
m
trust
● Network tbased models (Web of trust)
rust
?
e.g. Guha et al., 2004; Ziegler and Lausen, 2004; Golbeck et al., 2003
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 12

13. Existing Research on Trust
Trust ( )=?
What is the opposite of trust?
(Recommended: Marsh and Dibben, 2005)
Distrust ( )=?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 13

14. Existing Research on Trust
Trust ( )=?
What is the opposite of trust?
(Recommended: Marsh and Dibben, 2005)
?
Distrust ( )=?
Representations of distrust:
● Part of the trust value (e.g. Brondsema and Schamp, 2006)
e.g. -1 … 0 … 1
● Separate value (e.g Victor et al., 2006, Guha et al., 2004)
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 14

15. Existing Research on Trust
Trust ( )=?
Focus on active entities
(e.g. persons, agents, peers)
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 15

16. Shift
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 16

17. Let's
... make data
the central subject
of research on trust
in the Semantic Web
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 17

18. Let's
… conceive
research on trust as an effort
that fits in the area of
information quality research
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 18

19. Let's
… conceive
research on trust as an effort
that fits in the area of
information quality research
Common definition:
Fitness for use
of information
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 19

20. Let's
… conceive
research on trust as an effort
that fits in the area of
information quality research
● Multidimensional concept
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 20

21. Category* Criteria / Dimensions
Intrinsic Accuracy, Objectivity, ...
Contextual Completeness, Relevance, Timeliness, ...
Representational Conciseness, Understandability, ...
Accessibility
Let's Availability, Security, ...
… conceive
research on trust as an effort and Strong, 1996
*Classification by Wang
that fits in the area of
information quality research
● Multidimensional concept
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 21

22. Category* Criteria / Dimensions
Intrinsic Accuracy, Objectivity, ...
Contextual Completeness, Relevance, Timeliness, ...
Representational Conciseness, Understandability, ...
Let's
Accessibility Availability, Security, ...
… conceive
research on trust as an effort and Strong, 1996
*Classification by Wang
that fits in the area of
information quality research
● Multidimensional concept
● Trustworthiness of data is another such IQ criterion
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 22

23. Trustworthiness of Data
Definition: Subjective belief or disbelief in the truth of the
information represented by this data
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 23

24. Focus on Semantic Web Data
Trust ( )=?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 24

25. Focus on Semantic Web Data
Trust ( )=?
Trust ( )=?
http://cia..../Albania
http://.../unemp_rate
13.2 %
Trust ( )=?
Trust ( )=?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 25

26. Source-level Approaches
Trust ( )=Trust ( )
e.g.: Golbeck and Hendler, 2006;
Rowe and Butters, 2009;
Zaihrayeu, da Silva, and McGuinness, 2005
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 26

27. Source-level Approaches
Trust ( )=Trust ( )
e.g.: Golbeck and Hendler, 2006;
Rowe and Butters, 2009;
Zaihrayeu, da Silva, and McGuinness, 2005
What if multiple sources provide this data?
What if the data was republished as an aggregation?
What about implicit statements inferred from source data?
Are data sources the only relevant assessment criterion?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 27

28. Trustworthiness of Data
Definition: Subjective belief or disbelief in the truth of the
information represented by this data
● Decision to belief or disbelief affected by:
1. Provenance
2. Information quality
3. Other's opinion
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 28

29. Influence Category:
Provenance
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 29

30. Influence Category: Provenance
Trust ( )=?
● How was the creation of the data conducted?
● Who or what participated in the creation of the
data and how much do I trust this participant?
● To what extend does the input from which
the data was produced represents the truth?
● What happened to the data since its creation;
how likely is a manipulation?
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 30

31. Provenance
● provenir (French), meaning to come from
● How a data object in its current state came to be
● This history may start before the creation of the object
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 31

32. Provenance
● Provenance graphs represent the provenance
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 32

33. Provenance
● Basically, everything in a provenance graph
had / might have had an influence
on the data object
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 33

34. Provenance
● Basically, everything in a provenance graph
had / might have had an influence
on the data object
Trust( ) = fct( Trust( ), Trust( ), … )
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 34

35. Influence Category:
Information Quality
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 35

36. Influence Category: IQ
● Other IQ criteria may affect our belief in the truth of data
i.e. our trustworthiness assessment
● Example: lack of correctness, accuracy, or consistency
➔ Trustworthiness:
● Is a more abstract kind of IQ criteria
● Comprises multiple other criteria
Trust( ) = fct( Accuracy( ), Currency( ), … )
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 36

37. Influence Category: IQ
● Relevancy may depend on context:
Example: Completeness
Trust ( )
●
Trust( ) = fct( Accuracy( ), Currency( ), … )
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 37

38. Influence Category: IQ
● Relevancy may depend on context:
Example: Completeness
Trust ( )
●
Trust ( )
● Example: Currency
Trust( ) = fct( Accuracy( ), Currency( ), … )
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 38

39. Influence Category: IQ
● Relevancy may depend on context:
Example: Completeness
Trust ( )
●
Trust ( )
● Example: Currency
● Reflect relevancy by weighting the criteria
Trust( ) = fct( λAcc·Accuracy( ), λCur·Currency( ), … )
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 39

40. Influence Category:
Other's Opinion
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 40

41. Influence Category: Opinions
Trust( ) = fct( , , … )
● Similar to recommendation systems
● Two options:
● Use opinions of trusted consumers only
● Weight opinions by the consumers' trustworthiness
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 41

42. Take-away Summary
● Focus of trust research for the Semantic Web:
from an actor-centric view to a data-centric perspective
● Understand trustworthiness of Semantic Web data as
an information quality criterion
● Categories of factors that affect the assessment:
1. Provenance
2. Information quality
Trust ( )
3. Other's opinion
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 42

43. These slides have been created by
Olaf Hartig
http://olafhartig.de
This work is licensed under a
Creative Commons Attribution-Share Alike 3.0 License
(http://creativecommons.org/licenses/by-sa/3.0/)
Attribution:
● http://www.flickr.com/photos/rrrrred/3809362767/
● http://www.hasslefreeclipart.com
Olaf Hartig - Towards a Data-Centric Notion of Trust in the Semantic Web 43