Mechanisms for environments in multi-agent systems: Survey and opportunities <s> Research directions <s> Collective behaviour is often characterised by the so-called 'coordination paradox': looking at individual ants, for example, they do not seem to cooperate or communicate explicitly, but nevertheless at the social level cooperative behaviour, such as nest building, emerges, apparently without any central coordination. In the case of social insects such emergent coordination has been explained by the theory of stigmergy, which describes how individuals can effect the behaviour of others (and their own) through artefacts, i.e., the product of their own activity (e.g., building material in the ants' case). Artefacts clearly also play a strong role in human collective behaviour, which has been emphasised, for example, by proponents of activity theory and distributed cognition. However, the relation between theories of situated/social cognition and theories of social insect behaviour has so far received relatively little attention in the cognitive science literature. This paper aims to take a step in this direction by comparing three theoretical frameworks for the study of cognition in the context of agent-environment interaction (activity theory, situated action, and distributed cognition) to each other and to the theory of stigmergy as a possible minimal common ground. The comparison focuses on what each of the four theories has to say about the role/nature of (a) the agents involved in collective behaviour, (b) their environment, (c) the collective activities addressed, and (d) the role that artefacts play in the interaction between agents and their environments, and in particular in the coordination of cooperation. <s> BIB001 </s> Mechanisms for environments in multi-agent systems: Survey and opportunities <s> Research directions <s> In this paper, we focus on the problem of maintaining significant levels of cooperation in peer-to-peer (P2P) networks of selfish adaptive peers. We propose a simple algorithm that maintains high levels of cooperation in such a network while performing the collective task of file sharing. The algorithm is adapted from novel "tag" models of cooperation that do not rely on explicit reciprocity, reputation or trust mechanisms. A sequence of three simulation models is presented-starting with an abstract model of tag-based cooperation (TagWorld) and finishing with a P2P file-sharing model (FileWorld) that puts the technique to work. From analysis of extensive computer simulations, we demonstrate the technique to be scalable, robust, and decentralized; it requires no central servers or authorities. The algorithm is relatively simple: peers do not need to store additional trust information about other nodes or to perform significant additional processing. <s> BIB002
Mechanisms appear as key enablers of the environment idea, allowing a transition from concepts ('what') to engineering ('how'). Mechanisms can become incentives to exploit the environment in MAS by providing abstractions. Yet, the mechanisms in this article originate in practical MAS applications that do not completely cover the research in MAS. Other research areas are to be explored for the potential discovery of new mechanisms and the revision of the current classification. In this regard, future research could fruitfully address the following directions. 1. The survey work initiated in this article should be continued and refined with ongoing research activities. Similarly to the positive effect of design patterns on object-oriented programming, it is promising to provide developers with a set of mechanisms with clear guidelines on how to use them. To this end, two research directions can be relevant. On the one hand, it would be interesting to support designers in selecting suitable mechanisms according to the application requirements at hand. On the other hand, further studies can lead to engineering approaches on how to consistently compose existing mechanisms. 2. Novel mechanisms addressing under-investigated areas could be beneficial to the design of MAS. For example, in the specific case of interaction mediation, new mechanisms allowing agents to better structure and analyze a topology could lead to relevant results, especially for the role of the environment in the case of social interactions BIB002 . Besides, the aforementioned support for designers could help to determine innovative mechanisms in direct relation to the existing ones. 3. Most of the currently proposed mechanisms are at a low-level, in the sense that they enable interactions, provide context information, and wrap resources. Agents are expected to be situated at a higher level of abstraction and it would be interesting to search for new mechanisms at this level. Promising mechanisms may be the ones to hide the complexity of coordination issues (e.g. to engage in negotiations or argumentation), to regulate agent activities, and perhaps to provide mechanisms for trust management. Some other research endeavors also introduce potential extension of existing mechanisms, such as the 'cognitive stigmergy'  BIB001 .