A Logic for Agent Organizations

A Logic for Agent Organizations

Virgina Dignum (Utrecht University, The Netherlands) and Frank Dignum (Utrecht University, The Netherlands)
DOI: 10.4018/978-1-60566-256-5.ch009
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Abstract

Organization concepts and models are increasingly being adopted for the design and specification of multi-agent systems. Agent organizations can be seen as mechanisms of social order, created to achieve common goals for more or less autonomous agents. In order to develop a theory on the relationship between organizational structures, organizational actions, and actions of agents performing roles in the organization, we need a theoretical framework to describe and reason about organizations. The formal model presented in this chapter is sufficiently generic to enable the comparison of different existing organizational approaches to Multi-Agent Systems (MAS), while having enough descriptive power to describe realistic organizations.
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Introduction

Organizing is important in distributed computational systems, just as it is important in human systems. Researchers, within both the computer science and the organization theory fields, agree that many concepts and ideas can be shared between the two disciplines to better understand human organizations and to design more efficient and flexible distributed systems (So and Durfee; 1998; Cohen, 1986; Fox, 1981). However, due to its nature, organizational theory research tends to be not very formal from a computational perspective, which makes it difficult when moving from its use as a concept or paradigm towards using social and organizational concepts for the formalization of social concepts in Multi-Agent Systems (MAS).

Given such different views, the difficulty of comparing, analyzing and choosing a given approach becomes clear. Even if our aim is not to solve this problem, in this chapter we present initial steps towards the specification of a formal model for the study of agent organizations. The motivations for this model are twofold. On the one hand, the need for a formal representation of organizations, with their environment, objectives and agents in a way that enables to analyze their partial contributions to the performance of the organization in a changing environment. On the other hand, such a model must be realistic enough to incorporate the more ‘pragmatic’ considerations faced by real organizations. Most existing formal models lack this realism, e.g. either by ignoring temporal issues, or by taking a very restrictive view on the controllability of agents, or by assuming complete control and knowledge within the system (cf. Wooldridge, van der Hoek, 2005; Santos et al, 1997). Formal models for organizations that are able to deal with realistic situations, must thus meet at least the following requirements (Dignum, Tick, 2007):

  • 1.

    represent notions of ability and activity of agents, without requiring knowledge about the specific actions available to a specific agent

  • 2.

    accept limitedness of agent capability

  • 3.

    represent the ability and activity of a group of agents

  • 4.

    deal with temporal issues, in special the fact that activity takes time

  • 5.

    represent the concept of responsibility for the achievement of a given state of affairs

  • 6.

    represent organizational (global) goals and its link to agents’ activity, by relating activity and organizational structure

All of the above requirements are related to the more structural properties of an organization and will be met with the theory developed in this chapter. Furthermore, the following requirements are needed to enable complete representation and analysis of organization:

  • 7.

    deal with resource limitedness and the dependency of activity on resources (e.g. costs)

  • 8.

    represent organizational dynamics (evolution of organization over time, changes on agent population)

  • 9.

    represent organizations in terms of organizational roles or positions

  • 10.

    relate roles and agents (role enacting agents)

  • 11.

    deal with normative issues (representation of boundaries for action and the violation thereof)

Key Terms in this Chapter

(Agent or Group) Responsibility: Describes the fact that an agent or group of agents is in charge of realizing a certain state of affairs, and can therefore be made accountable for it.

Organizational Structure: Represents the relations between entities of an agent organization that are taken to be invariant through time. The main constructs found in it are roles, groups, and relationships between them.

(Agent or Group) Capability: Describes the intrinsic skill of an agent or group of agents to realize a certain state of affairs.

(Agent or Group) Ability: Refers to the potential to realize a certain capability, that is, the extrinsic conditions for the realization of a certain state of affairs.

Temporal Logic: System of rules and symbolism for representing, and reasoning about, propositions qualified in terms of time. It is often used to state requirements of hardware or software systems.

(Agent or Group) Stit: Meaning ‘sees to it that’ is the successful action of an agent or group of agents. A temporal stance on stit indicated that the result of activity is only valid in successor worlds.

Agent Organization: Comparable to human organizations, agent organizations are characterized by global goals and formalized social structures representing the stakeholder desired results. Can be seen as the structural setting in which agent interactions occur.

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