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Using social power to enable agents to reason about being part of a group. C.Carabelea , O.Boissier, C.Castelfranchi carabelea@emse.fr. Introduction. Autonomous agents have control over their local behaviour.

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Using social power to enable agents to reason about being part of a group l.jpg

Using social power to enableagents to reason about beingpart of a group

C.Carabelea, O.Boissier, C.Castelfranchi

carabelea@emse.fr


Introduction l.jpg

Introduction

  • Autonomous agents have control over their local behaviour.

  • One of the main challenges in multi-agent systems is the coordination of autonomous agents.

  • Bottom-up, emergent, coordination, usually based on

    • a model of relationships between goals, plans, etc. (e.g., TAEMS)

    • a reasoning about the dependencies between agents

  • Top-down coordination, usually based on:

    • organizational structures

    • norms, contracts

    • institutions

Powers and groups


Our objectives l.jpg

Our objectives

  • Our aim is not to engineer societies, but to engineer agents to understand societies.

  • We want to propose an unified model of reasoning about the constraints imposed by the coordination with other agents in both institutional and non-institutional contexts.

  • We will base this model on the social power theory:

    • social sciences’ theory describing the powers an agent has individually or with respect to other agents

    • informal, it needs to be formalized in order to enable agents to use it

  • The formalization presented in this paper is still an ongoing work

Powers and groups


Outline l.jpg

Outline

  • The powers of an agent

    • individual powers: executional, deontic, etc.

    • social powers: dependence and influencing power

    • institutional powers: due to authorities, norms and contracts

  • Using powers to reason about being part of a group

  • Other utilisations of the power theory

    • operations with power

    • agent autonomy

    • punishments and rewards

  • Conclusions and future work

Powers and groups


The basis of our model l.jpg

The basis of our model

  • We tried to keep our model as general as possible and not related to a specific model of agency or to a specific institutional model.

  • We describe the agents’ behaviour in terms of:

    • actions that need resources in order to be executed

    • goals achieved using plans formed by actions, resources and sub-goals

  • We use a number of predefined predicates that make the connection with existing, complementary, models (e.g., BDI):

    • has(X, resource), knows_how(X, action), goal(X, goal)

    • allowed_to(X, ...), can_empower(X, Y, ...)

Powers and groups


Individual powers l.jpg

Individual powers

  • Executional power: can_do

    can_do(X, Res) =d has(X, Res)

    can_do(X, Act) =d knows_how(X, Act) Ù(R needs(Act, R)  can_do(X, R))

    can_do(X, G) =d $plG achieves(plG, G) Ù can_do(X, plG)

    can_do(X, plG)=d "a plG can_do(X, a), where a is an action, resource or subgoal

  • Deontic power: entitled_to

    similar with can_do, but using the predicate allowed_to

  • Power of:

    power_of(X, P) =d can_do(X, P) Ù entitled_to(X, P)

Powers and groups


Example of an agent s powers l.jpg

resources

power_of

Example of an agent’s powers

A

Powers and groups


Social powers dependence and influencing power l.jpg

Social powers: dependence and influencing power

  • Agents depend on each other because they lack powers (Sichman et al.):

    • executional:

      depends_on(X, Y, G)=d plG achieves(plG, G)

      plGØcan_do(X,)  can_do(Y,)

    • deontic:

      depends_on(X, Y, G)=d Øentitled_to(X, G)  can_empower(Y, X, G)

  • An agent has the power of influencing another agent due to a dependence:

    X Y P power_of(X, P) Ù (G depends_on(X, Y, G) Ù goal(X, G))

    dep_infl_power(Y, X, P)

Powers and groups


Example of an agent s powers9 l.jpg

resources

power_of

dependence (Øentitled_to)

dep_infl_power

dependence (Øcan_do)

dep_infl_power

Example of an agent’s powers

A

B

C

Powers and groups


From bottom up to top down coordination l.jpg

From bottom-up to top-down coordination

  • There are many forms of dependences (Sichman et al.):

    • mutual, reciprocal, OR-dependencies, etc.

  • Dependence-networks have been proposed as a mechanism for agent coordination, e.g., agents reason about dependencies to choose coordination partners.

  • Top-down coordination models are based on different notions, like roles, hierarchies, norms, contracts, etc.

  • We use the term group to denote anything in the range of institutions, organizations, normative societies, teams, etc.

Powers and groups


Powers in groups contracts l.jpg

Powers in groups: contracts

  • Agents belong to groups:

    belongs_to(X, Gr)

  • A group can use the notion of contract between two agents:

    contract(X, Y, P, Gr)

  • We are not interested in how the group enforces the fulfillment of contracts (detection, punishments, etc.), but only that signing a contract in a group limits an agent’s behaviour:

    X,Y Gr belongs_to(X, Gr) Ù belongs_to(X, Gr) Ù P contract(X, Y, P, Gr)  contr_infl_power(Y, X, P)

Powers and groups


Example of an agent s powers12 l.jpg

resources

Group Gr

power_of

contract

dependence (Øentitled_to)

contr_infl_power

dep_infl_power

dependence (Øcan_do)

dep_infl_power

Example of an agent’s powers

A

D

B

C

Powers and groups


Powers in groups organizational structures l.jpg

Powers in groups: organizational structures

  • In a group, the behaviour of agents is not limited only by the dependences or the contracts signed towards other agents.

  • Agents play roles organized in hierarchies (authority relations):

    plays_role(X, R, Gr), authority_over(Gr, R1, R2, P)

  • Influencing power due to authority (organisational structure):

    X,Y Gr R1,R2plays_role(X, R1, Gr) Ù plays_role(Y, R2, Gr) Ù

    P authority_over(Gr, R2, R1, P)  org_infl_power(Y, X, P)

Powers and groups


Example of an agent s powers14 l.jpg

resources

Group Gr

R3

E

authority_over

power_of

org_infl_power

R1

contract

dependence (Øentitled_to)

contr_infl_power

dep_infl_power

dependence (Øcan_do)

org_infl_power

authority_over

dep_infl_power

R2

F

Example of an agent’s powers

A

D

B

C

Powers and groups


Powers in groups obligations l.jpg

Powers in groups: obligations

  • Norms have been used to regulate agents’ behaviour.

  • There is still an ongoing work on their definition and formalization, but generally norms are considered to be of three types: obligations, permissions and interdictions.

  • We use these predicates to define norms that target a role in a group and the object of these norms:

    permission(Gr, R, P), interdiction(Gr, R, P), obligation(Gr, R, P)

  • Influencing power due to a norm (an obligation):

    X Gr R plays_role(X, R, Gr) Ù P obligation(Gr, R, P) 

    norm_infl_power(group, X, P)

Powers and groups


Example of an agent s powers16 l.jpg

resources

Group Gr

R3

E

authority_over

power_of

org_infl_power

R1

contract

dependence (Øentitled_to)

contr_infl_power

dep_infl_power

obligation

dependence (Øcan_do)

org_infl_power

authority_over

dep_infl_power

norm_infl_power

R2

F

the group

Example of an agent’s powers

A

D

B

C

Powers and groups


Powers in groups permissions and interdictions l.jpg

Powers in groups: permissions and interdictions

  • The norms modify an agent’s deontic powers:

    X Gr R plays_role(X, R, Gr) ÙP permission(Gr, R, P) allowed_to(X, P)

    X Gr R plays_role(X, R, Gr) ÙP interdiction(Gr,R,P) Øallowed_to(X, P)

  • allowed_to is the source of an agent’s deontic power (entitled_to), which in turn is a component of an agent’s power_of.

  • Thus, by playing a role in a group an agent might increase its powers by receiving permissions, but also by receiving resources (e.g., money).

Powers and groups


Example of an agent s powers18 l.jpg

resources

resources

Group Gr

R3

E

authority_over

power_of

power_of

org_infl_power

R1

contract

dependence (Øentitled_to)

contr_infl_power

dep_infl_power

obligation

dependence (Øcan_do)

org_infl_power

authority_over

dep_infl_power

norm_infl_power

R2

F

the group

Example of an agent’s powers

A

D

B

C

Powers and groups


Example of an agent s powers19 l.jpg

resources

resources

Group Gr

R3

E

authority_over

power_of

power_of

org_infl_power

R1

contract

contr_infl_power

obligation

dependence (Øcan_do)

org_infl_power

authority_over

dep_infl_power

norm_infl_power

R2

F

the group

Example of an agent’s powers

A

D

B

C

Powers and groups


Reasoning about being part of a group l.jpg

Reasoning about being part of a group

  • When deciding whether to enter a group (e.g., an agent organization) or not (or to play a role or not), an agent can reason in terms of powers:

    • what are the powers that it will gain or lose?

    • who will be able to constrain its behaviour and why?

    • will it be able to constrain other agents’ behaviour?

    • what existing limitations of its behaviour are no longer valid?

  • This only complements and not replaces classical decision-making:

    • e.g. utility-based

    • it still has to decide whether to disobey a norm or not (by taking into account the associated punishments, the probability of being caught, etc.)

Powers and groups


Operations with power l.jpg

Operations with power

  • The powers of an agent are dynamic:

    • because of the dynamics of the environment or the actions of other agents’

    • because of the changes in the society

  • But there are also operations with powers that can be done by the agents:

    • Transfer of power

    • Putting at the disposal of an agent a power

    • Empowerment – especially interesting in agent institutions

    • Delegation / adoption – an agent adopting a goal from another agent implicitly gives it an indirect power to achieve that goal.

Powers and groups


Agent autonomy l.jpg

Agent autonomy

  • There are different types of autonomy in MAS: social autonomy, norm-autonomy, user-autonomy, etc.

  • The term autonomy is used in related work with two different meanings

    • Autonomy as independence (Castelfranchi)

      dep_independence(X, Y, P)=dØ dep_infl_power(Y, X, P)

    • Autonomy as the capacity of deciding about the adoption of a goal (Luck et al.)

      X,Y P dep_infl_power(Y, X, P) Ù delegation(Y, X, P) ÙØadoption(X, Y, P) 

      dep_autonomous(X, Y, P)

  • Same definitions for the other types of autonomy: org-autonomy, norm-autonomy, contract-autonomy.

Powers and groups


Defining punishments and rewards l.jpg

Defining punishments and rewards

  • We can use autonomy to define coordination-enforcement mechanisms. For example, for organizational autonomy:

    X,Y P org_infl_power(Y, X, P) Ù delegation(Y, X, P) ÙØadoption(X, Y, P) 

    org_autonomous(X, Y, P)

  • Disobeying the hierarchy should be punished:

    X Gr belongs_to(X, Gr) Ù Y P org_autonomous(X, Y, P)

    is_punished(X, Gr, punishment)

  • Non-mandatory cooperation is rewarded:

    X Gr belongs_to(X, Gr) Ù Y P delegation(Y, X, P) Ù adoption(X, Y, P) Ù

    Øorg_infl_power(Y, X, P)  is_rewarded(X, Gr, reward)

Powers and groups


Example of an agent s powers24 l.jpg

contr_autonomous

D

resources

resources

Group Gr

R3

E

authority_over

power_of

power_of

org_infl_power

R1

contract

contr_infl_power

punishment

obligation

dependence (Øcan_do)

org_infl_power

authority_over

dep_infl_power

norm_infl_power

R2

F

the group

Example of an agent’s powers

A

D

B

C

Powers and groups


Conclusions l.jpg

Conclusions

  • Reasoning about powers complements classical reasoning, agents can use powers to understand the constraints they face in a group.

  • An unified model of reasoning about constraints imposed by bottom-up (e.g., dependence-based) and top-down coordinations (e.g., organizations)

  • Can be used to classify and define different types of autonomy.

Powers and groups


Future work l.jpg

Future work

  • The formalization we propose is quite simple because we tried to keep this model as general as possible.

  • We intend to “tailor” our model (by defining key predicates like goal, norm, etc.) to existing coordination models in order to be able to endow agents with a power-based reasoning engine.

    • e.g., use TAEMS for bottom-up and MOISE+ for top-down coordination.

  • The same approach can be used to engineer institutions too.

  • For this we must formally define operations with powers (especially institutional empowerment).

Powers and groups


Example of an agent s powers27 l.jpg

resources

resources

Group Gr

R3

E

authority_over

power_of

power_of

org_infl_power

R1

contract

dependence (Øentitled_to)

contr_infl_power

dep_infl_power

obligation

dependence (Øcan_do)

org_infl_power

authority_over

dep_infl_power

norm_infl_power

R2

F

the group

Example of an agent’s powers

A

D

B

C

Powers and groups


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