institutional social dynamic dependence networks serena villata university of turin

Institutional Social Dynamic Institutional Social Dynamic Dependence NetworksDependence Networks

Serena Villata

University of Turin

S. Villata - Institutional Social Dynamic Dependence Networks

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Social Network TheorySocial Network Theory• Key technique in sociology, organizational

studies and economics.

• Connotation of complex sets of relationships among the members of social systems.

• Social network: social structure composed by nodes (individuals or organizations) and edges (relationships among individuals) that form a complex structure.


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Normative MASNormative MAS

• The presence of different types of entities with different capabilities inside the social network underlines the necessity of introducing social regulations.

• Relation between agent theory and social sciences such as sociology, philosophy, etc…

• Multiagent system research and sociology share the interest in the relation between micro-level agent behaviour and macro-level system effects.


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Power and Norms• Agents are heterogeneous, cooperative and have

different abilities.

• When an agent is not self-sufficient with respect to some goal, he can resort to some other agent, given that the latter cannot be self-sufficient itself in every respect.

• The aim of a normative MAS is regulating the behaviour of its agents thanks to norms and the institutional power that allows the introduction of new dependencies.


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Research Questions

• How to extend dependence networks to build social dependence networks which are able to model the dynamics of an institution?

• How to map the Institutional view of a multiagent system into the dynamic social network representation of it?


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The hypotetical Government• Roles: Prime Minister and other ministries.

• Material services to work: ministerial car, press statement, service of translation, etc…

• Institutional services: authorizations, delegations, etc…


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Agent View< A, F, G, X, goals: A → 2G, skills: A → 2X, rules: 2X → 2G>

Where

- goals: relates with each agent the set of goals it is interested in.

- skills: describes the actions each agent can perform.

- rules: relates sets of actions with the sets of goals they see to.

FG


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Institutional ViewInstitutional View

• Plurality of actors Plurality of actors →→ necessity of necessity of introducing institutions and social introducing institutions and social regulations.regulations.

• Not only obligations and permissions Not only obligations and permissions but also but also institutional powers: ability institutional powers: ability to change institutional reality.to change institutional reality.

• Social institutions exist thanks to the Social institutions exist thanks to the collective acceptancecollective acceptance of the of the institutional power. institutional power.

• Changes only according to its rules.Changes only according to its rules.


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The Institutional RealityThe Institutional Reality• Phisical realityPhisical reality associated to each agent, associated to each agent,

describing his beliefs, goals and capabilities.describing his beliefs, goals and capabilities.• The institution establishes a The institution establishes a new level of new level of

realityreality in the in the relationshipsrelationships between between involved actors that are associated to roles.involved actors that are associated to roles.

• This reality can be defined as the This reality can be defined as the public or public or institutional realityinstitutional reality. .

• This reality is associated to This reality is associated to institutional institutional goals, beliefs and capabilities: public goals, beliefs and capabilities: public character and change only according to character and change only according to accepted rules.accepted rules.


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Social Networks and Dependence Networks

• Social networks formalized as dependence networks.

• Social networks to study the relationships among the agents composing a MAS and the dynamics that arise from the interaction of these agents, modeling all by means of institutions.

• Multiagent systems give to social network theory new conceptual instruments as dependence networks.

• How to extend dependence networks to model institutional reality?


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Overview

• Power → capability of a group of agents to achieve goals.

• Dependence → possibility of a group Q of agents to satisfy goals of agents S.

• Institutional view → second level of reality.

• Institutional dependence network → abstract representation of the two levels.


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Agent’s Power

• Power is the capability of a group of agents to achieve some goals (theirs or of other agents) performing some actions without the possibility to be obstructed.

<A, G, power: 2A → 22G>


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Social Dependence Networks

• Agent described by a set of prioritized goals.• Global dependence relation that explicates how

an agent depends on the other agents for fulfilling its goals.

< A, G, dep, ≥ >

– dep: 2A x 2A → 22G -> relates with each pair of

sets of agents all the sets of goals on which the first depends on the second.

– ≥: A → 2G x 2G


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Example of Social Dependence Network

T

K

L

P

J

I F

g1

g1g2

g5

g5

g5 g5g5

g5

g5

g5 g5

g3

g4

g8

g6 g7

g5


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Institutional View< RL, IF, RG, X, igoals: RL → 2RG, iskills: RL → 2X,

irules: 2X → 2IF, roles: RL → A >

Where and

igoals: relates with each role the set of public goals it is committed to.

iskills: describes the institutional actions each role can perform.

irules: relates sets of institutional actions with the sets of institutional facts they see to.

IFFRG


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Dynamics of Institutional view

• In the material world, no elements can be added dynamically to the agents’ facts, skills and goals, since agents are autonomous by definition.

• In contrast, the institutional view can be changed in all its aspects since it is publicly attributed to agents by collective acceptance according to the constitutive rules of the institution.

• Institutional powers allow to change the structure of the institutional view, and thus, changing the powers of roles agents play, it consequently changes the structure of the social dependence network.


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Social DynamicDependence Networks (DDN)

• Property needed for the institution: the possibility to change the institution according to the constitutive rules it specifies by itself.

< A, G, ddep, ≥ >

– ddep: 2A x 2A x 2A → 22G relates with each triple of

sets of agents all the sets of goals on which the first depends on the second if the third creates the dependency.

– ≥: A → 2G x 2G


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Example of Institutional view• RL

– Minister of Finance (Fm), Prime Minister (Pm), Minister of Transport (Tm), Minister of Public Works (Wm) and Minister of Infrastructures (Im);

• RG– To obtain the authorization to built the bridge of Messina, to

obtain fundings to start a new series of public works in the major cities of Italy, to not be present to a council of ministers because of family problems.

• IX– Authorize to built the bridge of Messina, authorize fundings to

start a new series of public works in the major cities of Italy, give a delegation to minister Fm to give justification of absence.

• IF– Authorization to built the bridge of Messina, legislative powers

to role Pm ad interim, approved absence of role Wm.


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Example of Institutional view• RL = {Pm, Fm, Tm, Wm, Im};• RG = {pg1, pg2, pg3, pg4, pg5, pg6, pgN};• IX = {ixa, ixb, ixc, ixd, ixe, ixf , ixg, ixN};• IF = {ifa, ifb, ifc, ifd, ife, iff , ifN};

• roles (Fm) = {F}, roles (Pm) = {P}, roles (Tm) = {T}, roles (Wm) = {L}, roles(Im) = {I};

• igoals (Fm) = {pg6}, igoals (Pm) = {pg5}, igoals (Tm) = {pg1}, igoals (Wm) = {pg2, pg3, pg4}, igoals (Im) = {pg5};

• iskills (Fm) = {ixb, ixd, ixe, ixg, ixN}, skills (Pm) = {ixc, ixd, ixf }, skills (Tm) = {ixg}, iskills (Wm) = {ixg}, iskills (Im) = {ixa, ixg}

• irules ({ixa}) = {ifb}, irules ({ixb}) = {ifc}, irules ({ixc}) = {ife}, irules ({ixd}) = {ifa}, irules ({ixe}) = {ifd}, irules ({ixf }) = {ife}, irules({ixg}) = {iff }, irules({ixN}) = {ifN};


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DDN

T

K

L

P

J

I F

g1

g1g2

g5

g5

g5 g5g5

g5g5

g5 g5

g3

g4

g8

g6 g7

g5

g4

g8

Agent I with role Im has a bad Agent I with role Im has a bad behaviour, he is under investigation behaviour, he is under investigation

for corruption! Thus, the Prime for corruption! Thus, the Prime Minister deletes the power of role Im Minister deletes the power of role Im

to to authorize fundings for a call for authorize fundings for a call for tenders for the bridge of Messinatenders for the bridge of Messina

The Prime Minister The Prime Minister takes ad interim the takes ad interim the

power of role Im.power of role Im.


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ConclusionsConclusions

• Institutional powers applied to social networks.Institutional powers applied to social networks.• Institutional social networkInstitutional social network is a social network is a social network

that represents set of individuals regulated by that represents set of individuals regulated by institutional powers and with the application of institutional powers and with the application of social roles.social roles.

• A dynamic social dependence network represents various static social networks, by putting two networks into a single dynamic social dependence network.


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Future Work

• Definition of measures like social importance in dynamic dependence networks.

• Identification of coalitions inside a social dependence network.

• Definition of the concept of stability of a coalition, relating it to coalition’s dynamics.

• Extension to obligations and permissions.


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Bibliography• Boella, G. and Sauro, L. and van der Torre, L., Social

Viewpoints on Multiagent Systems, Proceedings of AAMAS'04, pp. 1358--1359, (2004)

• G. Boella, L. Sauro, and L. van der Torre, Admissible Agreements among Goal-directed Agents, Proceedings of IAT05. IEEE, (2005)

• Boella, G. and Sauro, L. and van der Torre, L., Strengthening admissible coalitions, Proceedings of ECAI'06, 195-199, (2006)

• Boella, G. and Sauro, L. and van der Torre, L., From social power to social importance, Web Intelligence and Agent Systems, IOS Press, pp. 393--404, (2007)

• Caire, P. and Villata, S. and van der Torre, L. and Boella, G., Conviviality Masks in Role-Based Institutions Multi-Agent Teleconferencing in Virtual Worlds, Proceedings of AAMAS'08, (2008)

institutional social dynamic dependence networks serena villata university of turin

Documents

social dependence networks

social institutions

social regulations

social structure

social sciences

institutional powers

institutional services

members of social systems