Alnemr tm symp-slides

Enabling Reputation Interoperability
through Semantic Technologies

Rehab Alnemr

HPI Research School
Chair “Internet Technologies and Systems”
of Prof. Dr. ChristophMeinel

Approaches?
Trust Management
2

Trust models
■ serve as a decision criterion for an agent to engage in activities

One of the approaches
■ Reputation-based approach
□ use reputation as a base for trust
□ closed domains: each has its own method to query, store, aggregate,
infer, interpret and represent reputation
□ Used in:
– Web communities (e-Markets, blogs, social networks)
– Services
– Software agents

Reputation.Interoperability (Semantic Technologies);

Concepts?
Reputation Approach
3

■ Reputation Target
users, movies, products, blog posts, tags, companies, services, software
agents, and IP addresses

■ Reputation Model
all of the reputation statements, events, and processes for a particular
context

■ Reputation Context
the relevant category for a specific reputation


Concepts?
Reputation Approach
4

■ Reputation Target
users, movies, products, blog posts, tags, companies, services, software
agents, and IPComputation Function
 addresses

 Communication Model
■ Reputation Model
all of the reputation statements, events, and processes for a particular
 Participants
context
 Resources
■ Reputation Context
 Representation Model
the relevant category for a specific reputation
 Storage

 Functionalities and Applications


Where…
Rep. Approach
5 Reputation of
Reputation of
users service providers

In Service-oriented Arch.

Reputation of
Reputation of business domains
services

Social/entertain
Slashdot E-Markets ment
News Online Reputation
Systems
Opinion & Business/Jobs
Activities network

…a typical buying decision

6


7


8


9

Ratings and Reviews
Online Markets
10

■ After buying, the consumer is asked to give his feedback in two ways:
a) stars ratings
b) by answering a seller-feedback questions with an option of leaving a
comment.
■ No obvious distinction -at the rating page- of what exactly being rated or
reviewed.

■ In one of our user studies:
Differentiate between 5 Stars and reviews

35% Did not know, thought
65% maybe product quality
Customer Service


Ratings in Online Markets
Online Markets
11

■ Only at the description page (policies)
□ stars rating is an overall rating of the product
□ detailed review page is for the buying experience = reviewing the
seller (order fulfillment, customer service, correct item description)

”If your comments include any of the following, your feedback is subject to
removal:
Product reviews: It is more appropriate to review product on the product detail
page....Customers reviews are for products”.

■ Three reputation attributes:
□ product quality
□ seller reputation
□ customer service


Our User Studies

12

Online Survey + interviews: Online Chocolate Store
200 users, different + detailed ratings
countries

■ test
□ how users perceive reputation
□ how many of reputation attributes the users consider
□ which of them the users focus on
□ used in the decision process with each other or separately?
□ their relation to the overall rating


User Survey:
http://www.kwiksurveys.com?s=ILNING_865460b6
Study 1
13

User Survey:
http://www.kwiksurveys.com?s=ILNING_865460b6
Study 1
14

Results

15 eBay Rating Frequency
(number,
40 Gold 14
Sometimes
60 %
stars)
21%
Stars and
% 65 Never
% detailed
Reviews %
other

No. of
20 Reviews
No. of
Reviews
% 40
80 High-Value 60 % Detailed
ratings
%
Stars %


Results

16 eBay Rating Frequency
(number,
40 Gold 14
Sometimes
60 %
stars)
21%
Stars and
% 65 Never
% detailed
Reviews %
other high seller reputation
conjoint
measure of
11 price & quality
% 50 Good Customer
39 Service
%
% other

No. of
20 Reviews
No. of
Reviews
% 40
80 High-Value 60 % Detailed
ratings
%
Stars %


Results: comparison bet. Rating styles

17


Results: comparison bet. Rating styles

18

no ”reviews” option available
 users explicitly asked for it to be added stating that this is the only
way to gather more information on a provider before selecting him


What does this mean?
Analysis
19
■ Confusion in interpreting the meaning of

□ rating styles
□ reputation values
■ Reputation of a seller or a product means more than one attribute

□ combination of attributes: neither represented nor clear from current
rating methods
■ Detailed ratings were preferred over stars ratings and high number-of-
reviews

■ Users tend to read reviews (comments and feedback) in order to decide on
a product or a seller


ChocStore
Study 2
20 ■ Online Chocolate Store

■ For our institution personal

■ Normal Online store functionalities

■ 2 choices of payments

■ 3 choices of delivery

■ prices were changed
significantly compared to
the procurement cost
(underpriced, overpriced)


Online Chocolate Store
Objectives
22

■ How many attributes are suitable for a review

■ What is the important aspect of each user’s rating

■ Based on the previous study, we show that several attributes - delivery
time for instance- affects rating

■ To examine categorized ratings with multiple attributes vs. overall ratings


Online Chocolate Store
Results
23

■ The overall rating does not always relate to the same attribute (i.e.
delivery, quality, price) -> overall rating does not convey or show the
meaning behind it

■ Delivery time affects delivery rating and sometimes overall rating

■ Prices always affect overall rating

■ Pick one attribute that is most important to your overall rating:

Rating Attributes
Delivery
23%
38.50% Price
38.50%
Quality


What does this mean?
Analysis
24

■ Users gave the same overall rating for different reasons

■ Some cared more about product quality, others cared for how fast the
delivery is

■ Average 4 attributes in the form was acceptable by all users

■ Singular formats of reputation is not enough

■ ignore the reasons and information behind the ratings

■ Users use several pieces of information to decide on a service provider


So?
Discussion
25

■ A more aware user

■ read textual reviews to find what he/she is looking for

■ Possible -> for human users though time consuming
Not Possible -> in other domains e.g. software agents or web services,

■ text analysis: a highly expensive task that can not be performed for every
transaction

■ A user seeking a provider checks for high reputed ones

■ assuming that the high reputation interprets into his own attribute of
selection


Why Rating is not enough?
No context
26 Bad E-Shop
Review

Business
Relying Party Owner/Seller/Facto
ry
Delivery
User Service
Delayed
Package

Context excluded from the reputation value
□ reputation query is too general
□ 3 different contexts
□ delivery, quality, price


Single Rating
27

■ Rating “used books”
□ is the rating for the book itself -> the user liked what he read
□ or the quality of the book -> was new and good printing
□ or the service provided by Amazon for example -> offering the
book, price, delivery, payment method, etc.


Different perceptions
28

Different representations, interaction styles and
trust rating scales


Different perceptions
29

Isolated reputation communities that have different:
□ perception of reputation
□ calculation of reputation
□ interpretation of reputation
□ overall reputation – not context related

Different representations, interaction styles and
trust rating scales


No portability
30


No portability
31

□ Starting from scratch for each domain
□ Cold start problem
□ No reputation information exchange


No portability
32

□ Starting from scratch for each domain
□ Cold start problem
□ No reputation information exchange
Solution
 Unify the representation not the calculation
 Define a generic reputation Ontology
 Embed more information- relating semantics
 Facilitate knowledge exchange


Ontologies
Why Ontologies?
33
Ontologies
Concepts & relationships used to describe & represent an area of
knowledge

■ creates a common understanding

■ specifies the factors -their explicit semantics - involved in computing
reputation

■ separates the definition of reputation from how it is calculated

■ enables the mapping between reputation concepts in different models

■ facilitates the use of existing mapping &integration techniques in IS for
reusing reputation info

■ reputation interoperability & cross community sharing of reputation
information


Competency Questions
Reputation Requirements
34

 Q1 Reputation definition
define the notion of reputation within the domain?

 Q2 Reputation Identity
entities? reputation roles such as source, target, evaluator, etc.?

 Q3 Reputation representation
in a single format? is it enough to express its meaning? how reputation will be
represented, communicated?

 Q4 Reputation statement
a reputation statement? what information does a reputation transaction hold?

 Q5 Reputation computation mechanism
is there a property that defines and describes the computation mechanism?


Cont. Competency Questions
Reputation Requirements
35
 Q6 Reputation context
a property that expresses the relation between a reputation value and the context of its
creation? combine its reputation in different contexts?

 Q7 Reputation factors
factors affecting reputation? does the source’s reputation affect reputation calculation?

 Q8 Reputation dynamics and temporal effect
change through time? properties that reflect the change in reputation values? time
validity? is the new value time-stamped?

 Q9 Reputation history
can we maintain the history of reputation values that an entity owned?

 Q10 Reputation expressiveness
can we define and describe the semantics of the involved factors, contexts, relations,
and concepts? is there a way to communicate the semantics of a reputation context?


Reputation Object Model
Representation
36
The RO model
■ Uses more information about the domain
□ the contexts and/or relevant quality criteria
■ Using this information, reputation is represented differently
□ as a developed object
■ The Reputation Object profiles an entity’s performance and has knowledge about
□ contexts
□ ratings values/reviews/feedback
□ computation functions
□ collecting method
Reputation Object
a profile of an entity’s performance


Reputation Object Ontology
RO Ontology
37


RO Ontology
38


RO Ontology
39


RO Ontology
40


Which Technology?
Used Technology
41
■ Developing interoperable reputation objects requires

■ structure and standardize reputation info and its relevant data

■ enable data integration

■ provide ways to relate the data to its explicit semantics

■ provide common data representation framework in order
to facilitate the integration of multiple sources to draw new
conclusions

Semantic
Technologies


What is Semantic Web?
Semantic Technologies
42

■ extension of the current web in which information is given well-defined
meaning, better enabling computers and people to work in cooperation

■ collection of standard technologies to realize a Web of Data where they are
linked & are understandable by machines

■ provide common data representation framework in order to facilitate the
integration of multiple sources to draw new conclusions

■ Goals
■ Standard Representation
■ Linkability and Integration
■ Automation
■ Reuse across applications


…define and structure
Semantic Technologies
43
Define Structure
■ Ontologies ■ RDF
Concepts &relationships used to ■ RDFa, microformats
describe & represent an area of ■ OWL
knowledge ■ …

Data
Integration
Phases


RO Ontology: OWL
RO Ontology
44
■ Developed using Protégé 3.4.4 OWL-DL

■ Vocabulary of RO Ontology:
■ to represent an entity's (foaf:Agent) reputation
■ an object (ReputationObject) has one or multiple
instances of class Criterion or QualityAttribute
■ each criterion instance has a ReputationValue
(currentValueand historyList) that has a set of
PossibleValues (as literals or resources URI)
■ a criterion is collected by a CollectingAlgorithm&
computed using a ComputationAlgorithm

■ Employing also known vocabulary
OWL, RDFS, FOAF, XSD, RDF Review, ..


Implementation: Library
RO Ontology
45


Using Semantic Technologies
Goals
46

 enabling reputation information exchange
 facilitate the integration of multiple sources to draw new conclusions,
 connecting data to its definitions and to its context
 achieving reputation interoperability
 Context-aware reputation
 ensuring understandability and reusability of the embedded information

Semantic
Technologies


A seller RO in e-Markets
Applications
47
■ Using GoodRelations ontologies to describe a seller and RO ontology to
describe its reputation

Criterion 1

Criterion 2


Usage Control in E-Markets
Applications
48
■ Using ROs for decisions during runtime allows revoking participants due to
their former behavior

■ Security settings is one of the RO criteria


Rule-based Reputation Systems
Applications
49
■ Using Rule Responder (Multi Agent Reasoning system) to deploy distributed
rule inference services
■ Agents/services communicate reputation objects or specific measures in
them

■ Reputation values used in the agent’s rule logic,
o e.g. deciding on a seller based on delivery method and review


Cloud Provider Selection
Applications
50
■ Selecting cloud providers based on their reputation & a consumer preference
list
■ Reducing the risks by selecting reputable SPs

From the detailed reputation
profile,
□ cross reference the quality
parameters requested by the
consumer and the
performance parameters
extracted from the providers’
reputation objects.


Personalized News Network
38
■ Real Experience
 We want to stay informed with real trusted news
 Online Social Network was the answer
■ 2 motivating facts:
 Delayed news in the mainstream media
 Fabricated news


Personalized News Network
38
■ Real Experience
 We want to stay informed with real trusted news
 Online Social Network was the answer
■ 2 motivating facts:
 Delayed news in the mainstream media
 Fabricated news
■ Filtered
□ Trends
□ Trusted networks


Thank You

Rehab Alnemr
(rehab.alnemr@hpi.uni-potsdam.de)

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