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

1. Using social power to enableagents to reason about beingpart of a group C.Carabelea, O.Boissier, C.Castelfranchi carabelea@emse.fr

2. 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

3. 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

4. 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

5. 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

6. 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

7. resources power_of Example of an agent’s powers A Powers and groups

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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