A meta-model for the analysis and design of organizations in multi-agent systems

1. Solved Problem

1) Heterogeneity of language. While heterogeneity has been considered as an important issue in multi-agent systems, there are no implemented systems, to our knowledge, that accept agents speaking different languages. Efforts to bring a standardized language such as KQML or ACL of the FIPA group, show that the problem of language heterogeneity has been considered so important that it required standardization methods to reduce language discrepancies.

 

2) Multiple applications and architectures. No implemented systems, to our knowledge, allow several applications with different objectives and different internal architectures to work concurrently on the same platform.

 

3) Security. While security is a major concern in distributed systems, no multi-agent techniques, to our knowledge, have been proposed to prevent agents from interacting with other agents. Any agent, in a system, is supposed to be able to interact with any other agent regardless of its capabilities, goals and authorizations.

 

2. How to Solve

(1)The concrete level

Agent: active entity that plays roles within groups.

Group: set of agents sharing common characteristics.

Role: abstract representation of the status, position, function of an agent within a group.

 

Note:

  • Agents may have several roles and may belong to several groups.
  • Two agents can’t communicate with each other if they don’t belong to the same group

The Core Model

Figure1 The Core Model

 

(2)The abstract, methodological level

The Methodological Model

Figure2 The Methodological Model

 

Group structure

Define a group structure as a tuple: clip_image006.

clip_image008 is a finite set of roles identifiers. It represents the enumeration of all possible roles than can be played by agents within a group.

clip_image010 is the interaction graph. More precisely, it is a labelled oriented graph specifying the valid interactions between two roles. clip_image012. The edge orientation correponds to the role initiating the interaction. Each edge represents an interaction initiated by clip_image014 with a role clip_image016 and named clip_image018.

clip_image020 is the interaction language. It is the chosen formalism for the individual interaction definitions. For each relation within the graph, we associate a unique protocol definition p to any edge clip_image022 within clip_image010[1]. clip_image025,clip_image027

 

Organizational structure

Define an organizational structure as a couple clip_image029.

clip_image031 is a set a valid group structures.

clip_image033 is the representative graph. It is a labelled graph where each edge clip_image035 is labelled where two roles clip_image037, with clip_image039 and clip_image041, and where clip_image043 and clip_image045 are roles which are included in the set of roles defined in the group structures clip_image047 and clip_image049, respectively.

Therefore, a representative structure definition between two groups A andB is an agent having simulteneously the role clip_image051 in group a and role clip_image053 in group b.

 

A market organization example

(a) The organizational and group structure of a market organization, (b) An actual market organization

Figure3 (a) The organizational and group structure of a market organization, (b) An actual market organization

 

We define three groups. The link between the two different interaction models is held by the broker role, which acts as a representative of the service provider group by the way of its broker role within this group. The clients interact with the broker to find a suitable service agent, and the contract group structure definition is aimed at ephemeral groups containing only the two agents involved in the final phase of a negociation.

A possible state of a market organization resulting from this organizational structure is shown in figure 3b.

 

参考文献:

[1] Ferber J., Gutknecht O.. A meta-model for the analysis and design of organizations in multi-agent systems. Proceedings on International Conference of Multi Agent Systems, 1998.

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