The Agent Oriented Ontology of Social Reality: Are Roles Agents

1. The Agent Oriented Ontologyof Social Reality:Are Roles Agents? Guido Boella Dipartimento di Informatica � Torino joint work with Leendert van der Torre CWI � Amsterdam & TUDelft

2. Guido Boella http://normas.di.unito.it NorMAS Project: Normative MultiAgent Systems Research question: how to build for MAS a social reality composed of groups, normative systems, organizations and legal institutions MAS composed of autonomous agents: behavior is directed by their beliefs and goals and maximize preferences

3. Guido Boella http://normas.di.unito.it Normative Multiagent Systems �Sets of agents whose interactions are norm-governed; the norms prescribe how the agents ideally should and should not behave. [...] Importantly, the norms allow for the possibility that actual behavior may at times deviate from the ideal, i.e., that violations of obligations, or of agents� rights, may occur.� (Jones & Carmo 2001)

4. Guido Boella http://normas.di.unito.it Construction of Social Reality Regulative norms: Obligations, prohibitions, permissions, � Searle�s constitutive norms: Something counts as something else. Legal classification of reality in term of institutional facts Regulate the creation of institutional facts: E.g., property, marriage, money, �

5. Guido Boella http://normas.di.unito.it Construction of social reality Searle�s construction of social reality�Some rules regulate antecedently existing forms of behaviour. For example, the rules of polite table behaviour regulate eating, but eating exists independently of these rules. Some rules, on the other hand, do not merely regulate an antecedently existing activity called playing chess; they, as it were, create the possibility of or define that activity. The activity of playing chess is constituted by action in accordance with these rules. Chess has no existence apart from these rules. The institutions of marriage, money, and promising are like the institutions of baseball and chess in that they are systems of such constitutive rules or conventions.

6. Guido Boella http://normas.di.unito.it Which is the right metaphor? Lakoff: Role of metaphor in cognition to conceptualize reality which is not bodily grounded. An ontology of social reality should disclose the metaphorical mapping we use to understand social reality We propose the agent metaphor for understanding social reality

7. Guido Boella http://normas.di.unito.it The intentional stance Dennet: attitudes like belief and desire are folk psychology concepts that can be fruitfully used in explanations of rational human behavior. For an explanation of behavior it does not matter whether one actually possesses these mental attitudes: we describe the behavior of an affectionate cat or an unwilling screw in terms of mental attitudes. Dennet calls treating a person or artifact as a rational agent the �intentional stance�. ma differenza: organizzazioni sono realt� sociale.ma differenza: organizzazioni sono realt� sociale.

8. Guido Boella http://normas.di.unito.it The importance of us �The possibility of ascribing goals, beliefs, and actions to collectives relies on the idea that collectives can be taken to resemble persons. [�] both factual and normative beliefs can be ascribed (somewhat metaphorically) to groups, both formal and informal, structured and unstructured.� Tuomela, 1995

9. Guido Boella http://normas.di.unito.it Hint of formalizazion Input/output logic Decisions

10. Guido Boella http://normas.di.unito.it Conditional attitudes Beliefs and goal are conditional mental attitudes represented by rules Different inferential properties: e.g. beliefs are transitive goals are not

11. Guido Boella http://normas.di.unito.it Input/Output Logic (Makinson & van der Torre) Let R ? Rul: a,..,d?x or (a,�d,x) Outi(R) is closure under set of rules Out1:SI Out2:SI,OR Out3:SI,CT Out4:SI,OR,CT

12. Guido Boella http://normas.di.unito.it Example Out4:SI,OR,CT

13. Guido Boella http://normas.di.unito.it Beliefs and goals Belief rules are used to compute consequences (a set of propositions) of decisions (sets of decision variables) The consequences of beliefs are used to compute which goals remain unsatisfied Agents try to minimize the goals left unsatisfied by decisions

14. Guido Boella http://normas.di.unito.it First roles� Which is the right metaphor for understanding roles? What do we learn from that for social reality? How do roles fit in the overall agent metaphor for social reality?

15. Guido Boella http://normas.di.unito.it Role role - 1606, from Fr. r�le lit. "roll (of paper) on which an actor's part is written" from O.Fr. rolle from L. rotula "small wheel," dim. of rota "wheel." From ETYMOLOGY DICTIONARY

16. Guido Boella http://normas.di.unito.it Expecting behavior Sociology: Roles specify expected behavior Thus the question becomes: Expected by whom or what? Behavior of whom or what? (the actor) How to describe the expected behavior?

17. Guido Boella http://normas.di.unito.it Expected behavior Expectations have a deontic character: expectation about ideal behavior Who has the expectation must be able to judge whether the actual behavior fits the expected one Who has the expectation can describe behavior Thus, expectations belong to agents

18. Guido Boella http://normas.di.unito.it Expectation and coordination Also expectations w/o a deontic character: predictions of behavior of others. Castelfranchi: anticipatory coordination is basic cognitive ability Gmytrasievicz and Durfee: recursive modelling Predicting the behavior of other agents is necessary to evaluate an agent�s own decisions when agents interfere in the environment

19. Guido Boella http://normas.di.unito.it Anticipatory coordination

20. Guido Boella http://normas.di.unito.it Behavior of the actor The actor has a behavior The actor has to understand the description of the expected behavior and implement it The actor has to reason about what is expected from him and the consequences of its behavior Thus, the actor is an agent

21. Guido Boella http://normas.di.unito.it Behavior of the agent The expected behavior is the result of a decision of an agent Thus a role is the description of the behavior of an agent Agents (and their behavior) are described and implemented by attributing them mental attitudes like beliefs and goals

22. Guido Boella http://normas.di.unito.it Our claim: roles are agents Roles are (descriptions of) agents Roles defined in terms of beliefs and goals Roles require the mechanism for anticipating the agent�s behavior: not the actor actual behavior but the one which is expected from the actor

23. Guido Boella http://normas.di.unito.it Example 1: international trade The buyer will arrange the payment as soon as the seller can prove that he shipped the goods. The bill of lading is issued by the carrier in return for the goods that he received from the seller. According to Article 10 of the CIMTG the Bill of Lading reliably indicates that the goods have been shipped in international trade procedures.

24. Guido Boella http://normas.di.unito.it Example 1: international trade Note that this article has normative element. Whether the Bill of Lading is evidence does not depend so much on whether a person is psychologically convinced by it, but the law simply stipulates that the buyer should consider this document as sufficient evidence.

25. Guido Boella http://normas.di.unito.it �should consider�? Autonomous agents cannot be forced to believe or want something. Either the law is wrong or it is referring to something else. In fact, the law is describing the expected behavior of an agent: it is describing a role.

26. Guido Boella http://normas.di.unito.it �should consider�? Wrong approach: Tan and Gordijn: should consider Bill (b) as proof of shipment (s) = O(B(b ? s)) Beliefs of agents cannot be accessible, O(B(b ? s)) is an obligation whose violation cannot be monitored.

27. Guido Boella http://normas.di.unito.it �should consider�? thus �should consider� means �act as if� The role is attributed the goal to pay (p) if there is the proof of shipment s: s ? p Note that s is not a fact, it is rather an institutional fact (Searle):the legal classification of reality expected from the role: b counts as s

28. Guido Boella http://normas.di.unito.it �should consider�? �expected from the role� means:the overt behavior is judged according to the beliefs attributed to the role if b and the role is attributed the belief b ? s and the goal s ? p If there is the bill of lading b, not paying (�p) is a violation of the expectation, since the role should have satisfied the goal p

29. Guido Boella http://normas.di.unito.it Interpretation of behavior The actual behavior of an agent is compared not with the expected one Not only decisions/actions are compared with the expected ones Actions have meaning in �context� (e.g., obligations are conditional) Also as �context� of an action is used the �context� believed by the role

30. Guido Boella http://normas.di.unito.it Example 1: international trade There is the bill of lading b The agent has to decide what to do He does not believe the good is shipped (�s) so he is goal s ? p is not enabled He knows that he will be judged according to the buyer role�s expectation (b ? s and s ? p) The role is expected to pay from its point of view: the goal s ? p is enabled since s The agent pays since he will be judged for his role

31. Guido Boella http://normas.di.unito.it Anticipatory coordination

32. Guido Boella http://normas.di.unito.it Counterargument The bill of lading counts as a proof for the trading organization/normative system, not only for the role Hence, it is not shown that it is necessary that roles have beliefs Wait�

33. Guido Boella http://normas.di.unito.it Example 2: contract Contract is defined as a statement/exchange of intentions. Can be statements be always reliable? Again, what the contract does is to create roles, descriptions of the behavior expected by the parties

34. Guido Boella http://normas.di.unito.it Example 3: dialogue Searle�s speech act are not useful in MAS: mental state is not accessible Walton&Krabbe: Speech acts commit the speaker What if he is lying? Speech acts describe the beliefs and goals of the role of speaker

35. Guido Boella http://normas.di.unito.it Example 3: dialogue Assertion �roles are agents� is modeled not in terms of beliefs of the agent but of the role he plays. Speech acts during the dialogue change the state of the role (its beliefs and its goals) The agent is expected to respect the role he builds with his speech acts

36. Guido Boella http://normas.di.unito.it Dialog games

37. Guido Boella http://normas.di.unito.it Preliminary summary The agent metaphor can be applied to explain roles What about the other social entities? If roles are descriptions of (expected) behavior, they depend on entities which are able to give and understand descriptions of behavior in terms of beliefs and goals

38. Guido Boella http://normas.di.unito.it Roles and social entities Roles are founded concepts (Guarino et al. 04): they depend on other entities These entities are able to describe behavior in terms of beliefs and goals Entities which include roles are agents, too (i.e., can be described as agents)

39. Guido Boella http://normas.di.unito.it Social entities are agents Are normative systems, organizations and groups agents? and if they are, which role have roles in them?

40. Guido Boella http://normas.di.unito.it Normative systems are agents Normative multiagent systems are dynamic social orders. Castelfranchi: a social order is a pattern of interactions among interfering agents ``such that it allows the satisfaction of the interests of some agent A''. (a shared goal, a value) Social delegation: an institution, on behalf of the other agents, has to achieve some goal which is part of the plans of all members of the group or institution.

41. Guido Boella http://normas.di.unito.it Normative systems are agents Social control: ``an incessant local (micro) activity of its units�� aimed at restoring the regularities prescribed by norms A dynamic social order requires a continuous activity for ensuring that the normative system's goals are achieved. The application of sanctions in response to violations cannot be taken for granted: it is a result of the decision of an agent:the normative agent

42. Guido Boella http://normas.di.unito.it Collective acceptance

43. Guido Boella http://normas.di.unito.it Your wish is my command Obligations formalized as desires or goals of normative system NS seen as an agent Goals of normative system which describe ideal behavior of system Other goals specify how social control is achieved (Hart�s instrumental norms) Specification of games in which agents take the (autonomous!) normative system into account. an agent considers whether its actions will lead to a sanction

44. Guido Boella http://normas.di.unito.it Obligations Oa,NS(x,s|Y) Y?x is goal of NS  (thus: ? out(GNS)) Y,?x?V(a,n) is goal of NS Y,V(a,n)?s is goal of NS Y??s is goal of agent a V(a,n) = violation by agent a of norm n s = sanction

45. Guido Boella http://normas.di.unito.it Games da ? Lit(Xa) decision a ca = Out(Ba,da ?db) consequencesa Optimal decision minim. unreached goals Ua={y?x?Ga | y?ca and x?ca} Agent a optimizes, given that b optimizes

46. Guido Boella http://normas.di.unito.it Example of game

47. Guido Boella http://normas.di.unito.it And beliefs? Agents have beliefs: either they are used in the metaphorical mapping or the agent metaphor is wrong But�

48. Guido Boella http://normas.di.unito.it Construction of Social Reality Constitutive norms are beliefs of the normative agent Institutional facts are just legal categories Constitutive rules regulate the creation of institutional facts: E.g., property, marriage, money, Constitutive rules are the connections between propositions believed by the normative agent:paper ? money

49. Guido Boella http://normas.di.unito.it x Counts As y in C C,x?y is belief of NS (thus ?out+(BNS)) Choose logic for counts-as conditional Not just a causal conditional! Important discussion on chaining: x counts as y, y counts as z => x counts as z

50. Guido Boella http://normas.di.unito.it Institutional facts as abstractions �A fenced field counts as property�: f ? p �Trespassing property is forbidden�: O(t|p) Property is a legal category which exists only in the beliefs of the NS Its function is to provide a context for the obligation (enabled basing on beliefs of NS) Institutional facts are abstractions for defining obligations on a legal classification of reality

51. Guido Boella http://normas.di.unito.it Delegation of power

52. Guido Boella http://normas.di.unito.it Behavior is sanctioned

53. Guido Boella http://normas.di.unito.it Modifying NS Propositional variables C changing NS add/remove belief rules add/remove goal rules Norms defined as goals and beliefs can be changed C are made true only as specified by belief rules of NS: constitutive norms e.g. contract ? add(G, x ? y) in BNS

54. Guido Boella http://normas.di.unito.it Behavior changes the NS

55. Guido Boella http://normas.di.unito.it Social ontology

56. Guido Boella http://normas.di.unito.it Social ontology

57. Guido Boella http://normas.di.unito.it Social ontology

58. Guido Boella http://normas.di.unito.it Social ontology

59. Guido Boella http://normas.di.unito.it Social ontology

60. Guido Boella http://normas.di.unito.it Social ontology

61. Guido Boella http://normas.di.unito.it MOST IMPORTANT

62. Guido Boella http://normas.di.unito.it Normative ontology

63. Guido Boella http://normas.di.unito.it Normative ontology

64. Guido Boella http://normas.di.unito.it Normative ontology

65. Guido Boella http://normas.di.unito.it Legal institutions

66. Guido Boella http://normas.di.unito.it Roles are agents Roles are described by the normative systems as agents via the AD relation: NS attributes them beliefs NS attributes them goals � Roles are played by other agents

67. Guido Boella http://normas.di.unito.it ROLES ARE AGENTS

68. Guido Boella http://normas.di.unito.it Groups are agents a. When they take a decision, they consider also the goals of the group and they try to maximize their fulfillment. Hence, they are committed to the joint activity. b. When they take a decision, they include in their decision actions which contribute to the efforts of the partners. Hence, they are committed to mutual support. c. When they take a decision, they recursively model the decisions of their partners and their effects under the assumption that the partners are cooperative, too. Hence, they are mutually responsive to each other.

69. Guido Boella http://normas.di.unito.it Organizations are agents Organizations (Burocracies in Ouchi�s terminology) are modelled as normative systems structured into functional areas and roles. Both functional areas and roles are modelled as agents: They are the �parts� of the organization

70. Guido Boella http://normas.di.unito.it Social ontology

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73. Guido Boella http://normas.di.unito.it Normative system and roles A normative system has roles (trias politica) policemen judge legislator

74. Guido Boella http://normas.di.unito.it Organizations are agents

75. Guido Boella http://normas.di.unito.it Organizations are agents

76. Guido Boella http://normas.di.unito.it Power and representation Delegation of powers represented by constitutive rules in organizations:�the signature of the CEO counts as a decision of the organization� But what is the signature of a role?It depends on the player of the role:when an agent enters a role, its actions counts as actions of the role:it�s a belief of the role

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81. Guido Boella http://normas.di.unito.it Role have instances Roles have a state which changes (AD): they must have instances. Social entities have instances, too The difference is that all social entities do not act in the real world. They have no associated decision variables (at a certain level of detail)

82. Guido Boella http://normas.di.unito.it Duties and roles When an agent enters a role (he becomes an actor) the expected behavior of the role becomes the obligation of the agent Joost Breuker: norms associated to roles, but responsibility is individual

83. Guido Boella http://normas.di.unito.it Duties and roles Eg.: if s ? p is a goal of a role R, the agent A playing role R becomes the bearer of the obligation OA(s | p) No transfer of obligations! These obligations are created by the institutional action which changes the role playing relation PL

84. Guido Boella http://normas.di.unito.it Permissions �An employee is permitted to use the fax machine of the firm� Beliefs of roles express also the means which the agents uses (planning rules): m ? f is a belief of the role employee, T ? f is one of its goals The means specified by the role to achieve a goal become the permissions: P(m)

85. Guido Boella http://normas.di.unito.it Duties of roles or of actors? Football rules: expulsion for a fault of a player (the actor of a role) Is the norms directed to the actor or to the role? Who is affected by the sanction?Maybe the actor does not care but the role (and indirectly the team) does.

86. Guido Boella http://normas.di.unito.it Steimann�s properties A role comes with its own properties and behaviour. Roles are descriptions of agents: they specify beliefs and goals. Obligations, permissions and powers refer to roles.

87. Guido Boella http://normas.di.unito.it Steimann�s properties 2. Roles depend on relationshipsThe �context� of a role is always a social entity like a normative system, an organization or a functional area.This entity is seen as an agent able to attribute mental states to other agents.Thus to create roles.

88. Guido Boella http://normas.di.unito.it Steimann�s properties 3. An object may play different roles simultaneously The role playing relation has no contraints. Since roles are not types we have no multiple inheritance problems

89. Guido Boella http://normas.di.unito.it Steimann�s properties 4. An object may play the same role several times, simultaneously Roles have instances which are related to agents by the role playing relation.

90. Guido Boella http://normas.di.unito.it Steimann�s properties 5. An object may acquire and abandon roles dynamically The role playing relation can be changed as any other component of a normative system

91. Guido Boella http://normas.di.unito.it Steimann�s properties 6. The sequence in which roles may be acquired and relinquished can be subject to restrictions The role playing relation, as an institutional fact, is changed by a power of an agent. Which are the possible powers is established by the normative system: thus they can be restricted by constitutive rules

92. Guido Boella http://normas.di.unito.it Steimann�s properties 7. Objects of unrelated types can play the same role The role playing relation is restricted to �agents�, but no further restrictions are necessary

93. Guido Boella http://normas.di.unito.it Steimann�s properties 8. Roles can play roles In principle, a role can be played by any agent, then also by another role

94. Guido Boella http://normas.di.unito.it Steimann�s properties 9. A role can be transferred from one object to another The role instance can be linked to another agent via the role playing relation (but obligations must be replaced)

95. Guido Boella http://normas.di.unito.it Steimann�s properties 10. The state of an object can be role-specific: �role played by an object should be viewed as a separate instance of the object� Roles have instances with their beliefs and goals

96. Guido Boella http://normas.di.unito.it Steimann�s properties 11. Features of an object can be role-specific: �an object responds according to the role in which it is being addressed� Powers are defined in terms of actions of roles.

97. Guido Boella http://normas.di.unito.it Steimann�s properties 12. Roles restrict access: �When addressed in a certain role, features of the object itself (or of other roles of the object) remain invisible� The agent can affect the normative system only if its actions counts as other actions in a role

98. Guido Boella http://normas.di.unito.it Steimann�s properties 13. Different roles may share structure and behaviour Roles, as descriptions of behavior, can be structured in a hierarchy

99. Guido Boella http://normas.di.unito.it Steimann�s properties 14. An object and its roles share identity: ``a role is a mask that an object can wear'� The organization the role belongs to sees the agent�s actions through the role he plays

100. Guido Boella http://normas.di.unito.it Steimann�s properties 15. An object and its roles have different identities (the so-called counting problem) Since roles have instances we can simply count role-instances

101. Guido Boella http://normas.di.unito.it Conclusions Role are agents�

102. Guido Boella http://normas.di.unito.it Bibliography A Game Theoretic Approach to Contracts in Multiagent Systems. IEEE Transactions on SMC-c, to appear Roles are agents.In Procs. of ICEC, 2004, Delft, 2004 Contracts as legal institutions in organizations of autonomous agents. In Procs. of AAMAS'04, New York, 2004 Delta: The social delegation cycle. In Procs. of DEON'04 Workshop, Madeira, 2004 The distribution of obligations by negotiation In Procs. of ECAI'04, Valencia, 2004 Groups as agents with mental attitudes. In Procs. of AAMAS'04, New York, 2004. Permission and authorization in policies for virtual communities of agents. In Procs. of P2P Workshop at AAMAS�04, NY, 2004 Regulative and constitutive norms in normative multiagent systems. In Procs. KR'04, Whistler, 2004 A formalization of coalition structures in MAS. In Procs. of ECAI'04 Attributing mental attitudes to normative systems. In Procs. of AAMAS'03, Melbourne 2003 Local policies for the control of virtual communities. In Procs. of IEEE/WIC WI�03, Halifax 2003 Permissions and obligations in hierarchical normative systems. In Procs. of ICAIL�03, Edinburgh 2003

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