Trust Modeling

(Introduction)Ing. Arnotka NetrvalovSeptember 2008

Trust modelingWhy? Where? What?Behaviour and trustTrust representationTrust visualizationTrust formingTrust, agents and MASCooperationResultsCan it be trusted?/ 25Fide, sed qui fidas, vide. It is an equal failing to trust everybody, and to trust nobody.[ChangingMinds.org]

WHY? WHERE?Phenomenon of everyday lifeInternete-banking credibilitye-commerce trustworthiness of partnerse-service quality, promptnessPC and computing/25Trust modeling

WHERE? WHAT?Computing and trust

P2P systems security (working together of nodes)GRID computing security (reliability of sources, users)AD HOC networks message integrity (node =server, router, client, malicious nodes, special protocols, cryptographic codes)MAS security dependability (malicious agent detection, migrating, selection of the best agent, systems optimization)Semantic web credibility of sources (machine information collection)/25Trust modeling

Trust definition

Trust (or symmetrically, distrust) is a particular level of the subjective probability with which an agent will perform a particular action, both before we can monitor such an action (or independently of our capacity of ever to be able to monitor it) and in a context in which it affects our own action. /25Trust modelingGambetta's definition was derived as a summary of the contributions to the symposium on trust in Cambridge, England, 1988.

Behaviour and trust

I trust him.How much do I trust him?How much I think, he trusts me ?

What does it mean? Can trust be measured? What is visual representation of trust?/25Trust modeling

Basic trust levels/25Trust modeling

Representation of trust value/25Trust modeling

Hysteretic trust loopAbsolute distrustBlind trustTrust value/25Trust modelingInterval

Graf1

111

0.950.990.9

0.750.970.7

0.60.80.55

0.5250.60.47

0.50.550.45

0.4750.530.4

0.40.450.25

0.250.30.03

0.050.10.01

000

Th

Th-

Th+

Ignorance

List1

Trust value

0000

0.10.050.0750.025

0.20.250.30.2

0.30.40.450.35

0.40.4750.520.425

0.50.50.550.45

0.60.5250.580.48

0.70.60.650.55

0.80.750.80.7

0.90.950.9750.925

1111

Trust value

1111

0.90.950.990.9

0.80.750.970.7

0.70.60.80.55

0.60.5250.60.47

0.50.50.550.45

0.40.4750.530.4

0.30.40.450.25

0.20.250.30.03

0.10.050.10.01

0000

List1

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Trust value

Distribuce mry dvry

List2

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Mra dvry

Distribun smyka dvry

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Absolutn nedvra

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Mra dvry

Distribun smyka dvry

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Absolutn nedvra

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Interval

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Trust measure

Trust value distribution

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Comlete distrust

Blind Trust

Interval

Trust visualizationTrust square: two relation for couple and one value per relationship /25Trust modeling

Trust visualizationBASIC:1 couple of reciprocal distrust 3 couple - one entity trusts the other one and the other entity distrustscompletely the first one5 couple - one entity trusts and the other one is indifferent7 couple - one entity is indifferent and the other distrusts the first one9 - both entities are indifferent to each other or no relationship between them/25Example: Trust in communityTrust modeling

Trust types personal trust between entity- unilateral - reciprocal

phenomenal trust to phenomenon (product)Example: Representation of personal trust in group/25Trust modeling

Personal trust forming - personal trust i-th entity to j-th entity- personal trust j-th entity to i-th entity - number of reciprocal contacts i-th and j-th entities - number of recommendations of j-th entity to i-th from others - knowledge (learning, testing set) - reputation of j-th entity at i-th entity - randomness, where 0

Phenomenal trust forming/25 - trust i-th entity in k-th product - number of recommendation of k-th product to i-th entity

- reputation of k-th product at i-th entity

- randomness, where 0

Trust model conceptBasic idea - intervention trust model/25---- control.. data communicationTrust modeling

Trust, agents and MAS /25Trust modeling

Software for agent modeling and simulation

RETSINA (Reusable Environment for Task-Structured Intelligent Networked Agents ) - Carnegie Mellon University Swarm (Swarm Intelligence) - Santa FE Research InstituteJADE (Java Agent DEvelopment Framework)

JADE - development of MAS(FIPA standards), middleware

Runtime environmentLibraries for development of agentGraphical tool package for administration and monitoring of agents/25Trust modeling

Cooperation selection of partners Application

Graph theory Game theory Risk - caution index Reciprocal trust

Trust matrix/25Trust modeling

Cooperation caution indexPayoff matrix r = (y -z) x= g = (x -y) w = (1- ) t = (w -x) z=(1- ) y= (1- ) (1- )/25Caution matrixCaution index Trust modeling

Cooperation - criteria of couple selectionTrust modelingCriteria of couple selection

Minimum:

1. means both of caution index2. maximum of caution index of evaluated couplesReduced caution matrix(pre-selected pairs)

Results personal trust (Trustor)/25Trust modeling

Graf8

0.270.140.340.840.740.79

s12 (r21)

s14 (r41)

s25 (r52)

s32 (r23)

s34 (r43)

s54 (r45)

S[i,j]

reputation

Trustee's reputation

tab

T-stept12t14t25t32t34t54

00.970.350.410.550.030.31

10.990.350.410.590.030.32

210.350.410.50.020.3

30.920.350.410.50.020.3

40.920.360.410.50.020.3

50.920.350.410.50.020.33

C-stepc12c14c25c32c34c54

0000000

1211200

2410000

3020000

4020000

5000003

D-stepd12d14d25d32d34d54

0000000

1111111

2301000

3001000

4021000

5000002

Rs12 (r21)s14 (r41)s25 (r52)s32 (r23)s34 (r43)s54 (r45)

0.270.140.340.840.740.79

Trust

0.970.350.410.550.030.31

0.990.350.410.590.030.32

10.350.410.50.020.3

0.920.350.410.50.020.3

0.920.360.410.50.020.3

0.920.350.410.50.020.33

t12

t14

t25

t32

t34

t54

step

trust

Trust-steps

ContR

024000

011220

010000

020000

000000

000003

0

1

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t[i,j] order

Cnumb

C-step (rows)

ConC

000000

211200

410000

020000

020000

000003

c12

c14

c25

c32

c34

c54

step

number of contacts

Contacts

ConC (2)

000000

211200

410000

020000

020000

000003

c12

c14

c25

c32

c34

c54

step

Number of contacts

Contacts-steps

Recom

000000

111111

301000

001000

021000

000002

d12

d14

d25

d32

d34

d54

number of recommendations

step

Recommendations

Recom (2)

000000

111111

301000

001000

021000

000002

d12

d14

d25

d32

d34

d54

number of recommendations

step

Recommendations - steps

Rep

0.270.140.340.840.740.79

s12 (r21)

s14 (r41)

s25 (r52)

s32 (r23)

s34 (r43)

s54 (r45)

S[i,j]

reputation

Reputation

Rep (2)

0.270.140.340.840.740.79

subject

s12 (r21)

s14 (r41)

s25 (r52)

s32 (r23)

s34 (r43)

s54 (r45)

reputation

Trustee's reputation

Picture

Picture

000000

111111

301000

001000

021000

000002

d12

d14

d25

d32

d34

d54

List3

000000

211200

410000

020000

020000

000003

c12

c14

c25

c32

c34

c54

0.970.350.410.550.030.31

0.990.350.410.590.030.32

10.350.410.50.020.3

0.920.350.410.50.020.3

0.920.360.410.50.020.3

0.920.350.410.50.020.33

t12

t14

t25

t32

t34

t54

step

trust

0.270.140.340.840.740.79

s12 (r21)

s14 (r41)

s25 (r52)

s32 (r23)

s34 (r43)

s54 (r45)

S[i,j]

reputation

Trustee's reputation

Results - cooperation

Example (n=15, =10, tij - random):

[0;6] c[0.45;0.15] t[0.96;0.82] [4;9] c[0.52;0.35] t[0.79;0.72] [4;13] c[0.19;0.51] t[0.78;0.94] [5;9] c[0.40;0.49] t[0.71;0.74] [5;10] c[0.36;0.50] t[0.72;0,79] [9;12] c[0.56;0.24] t[0.88;0.72] [12;14] c[0.40;0.36] t[0.83;0.81]/25Trust modeling

Can it be trusted?Trust in Math

The classic proof that 2 = 1 runs thus.

First, let x = y = 1. Then: x = y x2 = xy x2 - y2 = xy - y2 (x + y)(x - y) = y (x - y) x + y = y 2 = 1

Now, you could look at that, and shrug, and say /25Trust modeling

Dvra, prce a vsledkyTrust modelingMal dvra je pinou tenic a spor, asto vyvolanch neetickm i neprofesionlnm jednnm. Jejm projevem jsou skryt agendy a politikaen skupin. Bv zdrojem nezdrav rivality, vede k uvaovn vhra-prohra a st do defenzivn komunikace. Dsledkem je snen rychlosti a zven nmahy pi een kol.

Tm nejdleitjm faktorem ovlivujcm dvru jsou vsledky. Avak bt dvryhodnm, neznamen jen mt vsledky, ale tak doclit, aby o nich vdli i ostatn. Stephen M. R. Covey: Dvra: jedin vc, kter doke zmnit ve, Management Press, 2008[Stephen M. R. Covey: The Speed of Trust, Free Press, New York, 2006]/25

Thank you for your attention.

Trust modelingTrust modeling