Lawgoverned interaction Lotzi Blni EEL 5708 Background Based

Law-governed interaction Lotzi Bölöni EEL 5708

Background • Based on the work of Naftaly Minsky and Victoria Ungureanu at Rutgers University – The Moses toolkit • I find it interesting because it makes us look in a different way to the world of agents • You may find “laws” in other agent frameworks, simulation frameworks and games as well. EEL 5708

Introduction • Societies of agents need to be coordinated “the managing of dependencies between agents in order to foster harmonious interaction between them” (Malone and Crowston 1994) • “a flock of birds must coordinate its flight in order to stay in formation” • Example of coordination policy: Budgeted Consumption – A client X can present a query to the database only if it has a positive budget bx, available to it, and bx is reduced by one for each such query. – Budgets can be provided to individual clients by a designated regulator, and a client with a positive budget can give part of it to any of his peers. EEL 5708

Coordination with laws • The authors propose several principles regarding the implementation of multi-agent coordination. • The enforcement needs to be decentralized • Coordination policies need to be formulated explicitly (rather then implicitly in the code of the agents) • It should be possible to deploy and enforce a policy incrementally, without exacting any cost from agents and activities not subject to it. EEL 5708

Principle 1: Enforcement • “A coordination policy for an open group need to be enforced” • Security issues • Disparate members of an open group which might have been built independently might have little reason to trust each other. EEL 5708

Principle 2: Decentralization • The enforcement mechanism should not require central control. • Easiest, with a centralized coordinator. – Not scalable, the coordinator is the bottleneck – Single point of failure. • Many laws are local in nature (for instance the one about budgeted consumption) EEL 5708

Principle 3: Separation of policy from mechanism Coordination mechanisms should be made explicit, and be enforced by the means of a single mechanism that can implement a wide range of policies in a uniform manner. • Large, conglomerate systems are likely to employ many different coordination policies. • A single agent might need to operate in multiple groups, not foreseen during its design EEL 5708

Principle 4: Incremental deployment One should be able to deploy and enforce a policy incrementally, without exacting any cost from agents and activities not subject to it. • In a large system, if deployment cannot be done incrementally, without making any requirements of the rest of the system, it probably cannot be done at all. EEL 5708

Discussion • Are the principles reasonable? • Do they match what happens: – On the internet? – In the human society? – Animal world? EEL 5708

Formalism • Law Governed Interaction (LGI) is a mode of interaction that allows a heterogeneous group of agents to interact with each other with confidence that an explicitly specified set L of rules of engagement – called the law of the group – is complied with. • “L-group” G <L, A, CS, M> – – L law – an explicit and enforced set of rules of engagement A a set of agents members of the group CS a set of control states, one per member of the group M a set of messages that can be exchanged, under law L between the members (L-messages) EEL 5708

Details • The law of a given group G is global with respect to G, but it is defined locally at each member of it. • The law is defined over certain types of events at the agents, mandating the effect that any such event should have. Events include sending and receiving messages. • The ruling of a law for an event e depends only on the event e and the control state CS of the agent. • The ruling of the law at a given EEL 5708