ESTADO DE RESULTADOS INTEGRALES

As work interactions between people and enterprises are moving towards ‘virtual’ enterprises in which the different parties have autonomous activity, efficient commu- nication and coordination between units and the design of equitable structures and processes are becoming essential in the well-being and the development of an organi- sation [Ancona et al.,2003]. In order to achieve sustainable adaptability and advantage to the environment, organisational models specifying the structure of societies have appeared, and during the last years they have played an important role in the design of information systems.

There are several definitions of what an organisation exactly means. Indeed, the word “organisation” is a complex word that has several meanings. In [Gasser,1992], Gasser proposed the definition of organisation to which we subscribe:

“An organisation provides a framework for activity and interaction through the definition of roles, behavioural expectations and authority relationships (e.g. control).”

According to Ferber et al., several main features of organisations can be derived from the various definitions in the literature [Ferber et al.,2004]:

1. An organisation constitutes of agents (individual members) that exhibit some behaviour.

2. The overall organisation may be split into partitions that may overlap (also called partition groups).

3. Agent behaviours are functionally associated with the general organisation ac- tivity (notion of role).

4. Agents are engaged in dynamic relationships (also called patterns of activities [Gasser, 1992]) which may be “typed” using a classification of roles, tasks or protocols, describing in this way a form of supra-individuality.

5. Types of behaviours are connected via relationships between roles, tasks and protocols.

2.2.1.1 The Concept of Role

Role theory [Hindin, 2007] has been generally concerned with the way individuals of particular social positions manifest patterns of behaviour as well as the way other individuals are expected to behave within context-specific situations. In a social envi- ronment, individuals take role positions and their performance is determined by social norms, demands and rules, while social values will determine which norms and rules will be directed to what role positions.

Given the significance of the social aspect in organisational modelling, an important element when considering agent design is the concept of role. A role is a description of an abstract behaviour of agents. A role might describe the constraints (obligations, requirements, skills) that an agent will have to satisfy to obtain a role, the benefits (abilities, authorisation, profits) that an agent will receive in playing that role, and the responsibilities associated with it. It can also be the placeholder describing the templates of interactions in which an agent enacting that role will have to perform4_.

Much of the work in the relevant literature place roles in the core of the organisa- tional description. While describing the Gaia framework in [Wooldridge et al., 2000], Wooldridge , Jennings and Kinny associate responsibilities, permissions, activities, and protocols to roles and propose a practical definition of computational organisations based solely on various interacting roles:

“We view an organisation as a collection of roles, that stand in certain relationships to one another, and that take part in systematic institutionalised patterns of interactions with other roles.”

In [Dignum, 2004] Dignum explains how a society’s objectives can be broken down into role objectives. Then, the whole society can be considered as a super-role, the ob- jectives of which are represented by organisational roles. The way these objectives are achieved depends on the requirements and characteristics of the specific domain. By specifying collaboration patterns, role models define high-level relationships between society members without fixing a priori the complete interaction process.

Dignum also explains how roles can be organised into groups, as a way of referring to a set of roles. She shows how useful this in an interaction scene5_{where a participant can}

be enacting one of several roles. She underlines the importance of dividing roles into groups as this allows to specify norms that must hold for all enactors in the group. This way, roles and groups of roles permit to ‘split’ the society objectives into role objectives, delegating in this way norms to enactors of roles in the group.

Finally, it is possible to define role dependencies between roles for the realisation of some objectives. This permits to indicate high-level dependencies between society members without necessarily specifying details of the type of coordination needed to distribute and achieve the objectives between them.

2.2.1.2 Organisational Frameworks

There are several organisational frameworks in the literature, but in this section we will review the most relevant to our work, as they include some sort of norms: MOISE [Hannoun et al.,2000] and OperA [Dignum,2004].

MOISE (Model of Organization for multI-agent SystEms) [Hannoun et al.,2000] presents an organisational model for multi-agent systems, focusing on the aspect of roles (which constrain the action possibilities for each agent and define the activities that an agent can perform), organisational links (which regulate the interactions that the agents can have between them) and groups (which define who can cooperate with whom). Further to this, in [H ¨ubner et al.,2002] the authors present the Moise+frame- work, an extension of MOISE. The main contribution of this extension is the distinc- tion of the three aspects of an organisation used separately in MOISE: the structural aspect (including roles structure and inheritance, group clustering of roles and differ- ent types of links such as compatibility, authority, acquaintance and communication between agent roles), the functional aspect (including global plans, tasks etc.) and the deontic aspect (including norms, laws etc) of the model. While MOISE focuses on the organisational structure providing no particular normative layer, Moise+ gives more emphasis on the complex relationships between actors as well as their rights and du- ties6.

5_{An interaction scene, or scene, normally refers to a set of dialogical activities between agents in the}

same way theatre scenes are played. Agents (actors) engage in dialogs with respect to their assigned role (character).

6_{An extension of Moise}+ _{with a more powerful notion of norms, called Moise}Inst_{, is described in}

OperA, described by Dignum in [Dignum,2004], is a framework for specifying organi- sations founded on the concept of social contracts. The OperA framework is composed of three components, Organisational Model (OM), Social Model (SM) and Interaction Model (IM):

• The OM describes the abstract specification of the organisation. It consists of a social structure (roles and the dependencies between the agents) and an interac- tion structure (describing possible interactions between agents). Additionally, a normative structure describes role norms (normative expressions that apply to roles) as well as scene and transition norms (expected conduct within a scene and restrictions over the transition from a scene to another, respectively).

• The SM describes the role enactment by the agents. This is done via social contracts, in a way that whenever an agent enacts a specific role, then the agent is adopting the terms of the contract associated with it. These terms represent the agent’s responsibilities within the framework.

• The IM specifies the interactions between the agents. This is done via pre- specified scenes (not defining how objectives can be achieved as this is left to the designer’s choice) and landmarks (partially ordered descriptions of desirable intermediate states) to be brought about within the scenes.

One of the strengths of OperA (being a model applicable to both human and soft- ware agents) is also the main limitation, as the framework provides no support to (semi-)automatically generate OperA-aware software agents (two frameworks based on OperA, namely OMNI and ALIVE, partly provide such functionality and will be discussed in Section2.2.2.3.3).

For a long time the notion of organisations and the notion of institutions were two distinct, separate views on modelling MAS governance. Nevertheless, in [Ferber et al., 2004] Ferber et al. proclaim that an organisation is made of two aspects: a structural aspect (also called static aspect) and a dynamic aspect. The structural aspect of an organ- isation consists of two parts: a partitioning structure and a role structure. A partitioning structure shows how agents form groups and how groups are related. A role struc- ture is defined, for every group, by a set of roles and the relations between them. This structure defines also the set of restrictions that agents should comply with to play a particular role and the benefits associated with that role. The dynamic aspect of an organisation is associated with the institutionalised templates of interactions that are specified within roles (norms). According to Ferber et al. it additionally defines the modalities to create, kill, enter groups and play roles, the way these are applied and the way organisation subdivision and role structuring are associated with an agent’s behaviour.

The last points form part of the institutional aspect of the organisation. While organ- isations provide the main concepts for an abstraction of social structures, they lack coordination frameworks that imitate the coordination structures within an organisa- tion. That is where institutions come into force. Institutions enforce the organisational

aims of the agent society and dictate a performative structure (i.e. a description of how scenes are interconnected through different types of transitions and how agents, via different roles, participate in these scenes) and a dialogical framework between members of the society [Noriega and Sierra, 2002; Sierra et al., 2001]. The benefit of institutions lies in their ability to provide legitimacy and security by providing social conventions and setting up a normative framework for their members. We explain more about institutions in Section2.2.2.