We consider the problem of detecting norm violations in open multi-agent systems (MAS). We show how, using ideas from scrip systems, we can design mechanisms where the agents comprising the MAS are incentivised to monitor the actions of other agents for norm violations. The cost of providing the incentives is not borne by the MAS and does not come from fines charged for norm violations (fines may be impossible to levy in a system where agents are free to leave and rejoin again under a different identity). Instead, monitoring incentives come from (scrip) fees for accessing the services provided by the MAS. In some cases, perfect monitoring (and hence enforcement) can be achieved: no norms will be violated in equilibrium. In other cases, we show that, while it is impossible to achieve perfect enforcement, we can get arbitrarily close; we can make the probability of a norm violation in equilibrium arbitrarily small. We show using simulations that our theoretical results hold for multi-agent systems with as few as 1000 agents---the system rapidly converges to the steady-state distribution of scrip tokens necessary to ensure monitoring and then remains close to the steady state.
These approaches are distributed, but the responsibility for monitoring still lies with the normative organisation, and the cost of monitoring is borne by the MAS, either in the cost of running additional system components which monitor and regulate interactions ( @cite_2 @cite_4 ) or by paying some agents to monitor the rest ( @cite_18 ). Fagundes :14a have explored the tradeoff between the efficiency and cost of norm enforcement in stochastic environments, to identify scenarios in which monitoring can be funded by sanctions levied on violating agents while at the same time keeping the number of violations within a tolerable level. However, in an open multi-agent system, approaches in which norm enforcement is based on sanctioning ( @cite_14 @cite_0 ) may be susceptible to sybil attacks; sanctioned agents may simply leave the system and rejoin under a different id. In contrast, in our approach, the cost of monitoring is borne by the agents using the MAS. Moreover, agents cannot benefit by dropping out and rejoining the system, and monitoring is m-resilient against collusion by monitoring agents.
@cite_18 @cite_14 @cite_4 @cite_0 @cite_2
137085984 2125646867 2165208522 57397232 2161520603
The subject of this paper is the cost of enforcement, to which we take a satisficing approach through the examination of marginal cost-benefit ratios. Social simulation is used to establish that less enforcement can be beneficial overall in economic terms, depending on the costs to system and or stakeholders arising from enforcement. The results are demonstrated by means of a case study of wireless mobile grids (WMGs). In such systems the dominant strategy for economically rational users is to free-ride, i.e. to benefit from the system without contributing to it. We examine the use of enforcement agents that police the system and punish users that take but do not give. The agent-based simulation shows that a certain proportion of enforcement agents increases cooperation in WMG architectures. The novelty of the results lies in our empirical evidence for the diminishing marginal utility of enforcement agents: that is how much defection they can foreclose at what cost. We show that an increase in the number of enforcement agents does not always increase the overall benefits-cost ratio, but that with respect to satisficing, a minimum proportion of enforcement agents can be identified that yields the best results. Social order in distributed descentralised systems is claimed to be obtained by using social norms and social control. This paper presents a normative P2P architecture to obtain social order in multi-agent systems. We propose the use of two types of norms that coexist: rules and conventions. Rules describe the global normative constraints on autonomous agents, whilst conventions are local norms. Social control is obtained by providing a non-intrusive control infrastructure that helps the agents build reputation values based on their respect of norms. Some experiments are presented that show how communities are dynamically formed and how bad agents are socially excluded. The design and development of open multi-agent systems (MAS) is a key aspect in agent research. We advocate that they can be realised as electronic institutions. In this paper we focus on the execution of electronic institutions by introducing AMELI, an infrastructure that mediates agentsý interactions while enforcing institutional rules. An innovative feature of AMELI is that it is of general purpose (it can interpret any institution specification), and therefore it can be regarded as domain-independent. The combination of ISLANDER [5] and AMELI provides full support for the design and development of electronic institutions. Due to external requirements we cannot always construct a centralized organization, but have to construct one that is distributed. A distributed organization is a network of organizations which can locally observe and control the environment. In this paper we analyze how norms can be enforced through the joint effort of the individual local organizations. Norm violations are detected by monitoring. Sanctioning compensates the violations of norms. The main problem is to map the required data for monitoring, and the required control capabilities for sanctioning, to the local observe control capabilities of organizations. Our investigation focuses on exploring the solution space of this problem, the properties of proper solutions and practical considerations when developing a solution. When agents make decisions, they have to deal with norms regulating the system. In this paper we therefore propose a rule-based qualitative decision and game theory combining ideas from multiagent systems and normative systems. Whereas normative systems are typically modelled as a single authority that imposes obligations and permissions on the agents, our theory is based on a multiagent structure of the normative system. We distinguish between agents whose behavior is governed by norms, so-called defender agents who have the duty to monitor violations of these norms and apply sanctions, and autonomous normative systems that issue norms and watch over the behavior of defender agents. We show that autonomous normative systems can delegate monitoring and sanctioning of violations to defender agents, when bearers of obligations model defender agents, which in turn model autonomous normative systems.