Agent Based Modeling and Simulation: An Informatics Perspective

The term computer simulation is related to the usage of a computational model in order to improve the understanding of a system's behavior and/or to evaluate strategies for its operation, in explanatory or predictive schemes. There are cases in which practical or ethical reasons make it impossible to realize direct observations: in these cases, the possibility of realizing 'in-machina' experiments may represent the only way to study, analyze and evaluate models of those realities. Different situations and systems are characterized by the presence of autonomous entities whose local behaviors (actions and interactions) determine the evolution of the overall system; agent-based models are particularly suited to support the definition of models of such systems, but also to support the design and implementation of simulators. Agent-Based models and Multi-Agent Systems (MAS) have been adopted to simulate very different kinds of complex systems, from the simulation of socio-economic systems to the elaboration of scenarios for logistics optimization, from biological systems to urban planning. This paper discusses the specific aspects of this approach to modeling and simulation from the perspective of Informatics, describing the typical elements of an agent-based simulation model and the relevant research.Multi-Agent Systems, Agent-Based Modeling and Simulation

Agent communication and artificial institutions

In this paper we propose an application-independent model for the definition of artificial institutions that can be used to define open multi-agent systems. Such a model of institutional reality makes us able also to define an objective and external semantics of a commitment-based Agent Communication Language (ACL). In particular we propose to regard an ACL as a set of conventions to act on a fragment of institutional reality, defined in the context of an artificial institution. Another contribution of the work presented in this paper is an operational definition of norms, a crucial component of artificial institutions. In fact in open systems interacting agents might not conform to the specifications. We regard norms as event-driven rules that when are fired by events happening in the system create or cancel a set of commitments. An interesting aspect of our proposal is that both the definition of the ACL and the definition of norms are based on the same notion of commitment. Therefore an agent capable of reasoning on commitments can reason on the semantics of communicative acts and on the system of norm

Ontology acquisition and exchange of evolutionary product-brokering agents

Agent-based electronic commerce (e-commerce) has been booming with the development of the Internet and agent technologies. However, little effort has been devoted to exploring the learning and evolving capabilities of software agents. This paper addresses issues of evolving software agents in e-commerce applications. An agent structure with evolution features is proposed with a focus on internal hierarchical knowledge. We argue that knowledge base of agents should be the cornerstone for their evolution capabilities, and agents can enhance their knowledge bases by exchanging knowledge with other agents. In this paper, product ontology is chosen as an instance of knowledge base. We propose a new approach to facilitate ontology exchange among e-commerce agents. The ontology exchange model and its formalities are elaborated. Product-brokering agents have been designed and implemented, which accomplish the ontology exchange process from request to integration

Artificial institutions: a model of institutional reality for open multiagent systems

Software agents' ability to interact within different open systems, designed by different groups, presupposes an agreement on an unambiguous definition of a set of concepts, used to describe the context of the interaction and the communication language the agents can use. Agents' interactions ought to allow for reliable expectations on the possible evolution of the system; however, in open systems interacting agents may not conform to predefined specifications. A possible solution is to define interaction environments including a normative component, with suitable rules to regulate the behaviour of agents. To tackle this problem we propose an application-independent metamodel of artificial institutions that can be used to define open multiagent systems. In our view an artificial institution is made up by an ontology that models the social context of the interaction, a set of authorizations to act on the institutional context, a set of linguistic conventions for the performance of institutional actions and a system of norms that are necessary to constrain the agents' action

An operational approach to norms in artificial institutions

The notion of artificial institution is crucial for the specification of open and dynamic interaction frameworks where heterogeneous and autonomous agents can interact to face problems in various fields, like for instance electronic commerce, business-to-business (B2B) applications, and personal assistant applications. In our view the specification of artificial institutions requires a clear standard definition of some basic concepts: the notion of ontology, authorizations, conventions, and norms. In this paper we propose an operational approach to the definition of norms that is mainly based on the generation of commitments. These norms can be employed to verify if the interacting agents are behaving in accordance with the normative specification of the system. In particular we regard norms as event-driven rules that are fired by events happening in the system and then modify commitments affecting the agents having a certain role. We will discuss the crucial differences between the notion of authorization and permission and how the notion of permissions, obligations, and prohibitions can be expressed in our model. We will investigate the connections among the specification of different artificial institutions, in particular how an institution can enrich or further regulate the entities defined in another one. Finally we will briefly present the specification of the Dutch Auction Institution and of the Auction House Institution in order to exemplify the model presented in this paper

Artificial institutions: a model of institutional reality for open multiagent systems

Software agents’ ability to interact within different open systems, designed by different groups, presupposes an agreement on an unambiguous definition of a set of concepts, used to describe the context of the interaction and the communication language the agents can use. Agents’ interactions ought to allow for reliable expectations on the possible evolution of the system; however, in open systems interacting agents may not conform to predefined specifications. A possible solution is to define interaction environments including a normative component, with suitable rules to regulate the behaviour of agents. To tackle this problem, we propose an application-independent model of artificial institutions that can be used to define open multiagent systems. With respect to other approaches to artificial (or electronic) institutions, which mainly focus on the definition of the normative component of open systems, our proposal has a wider scope, in that we model the social context of the interaction, define the semantics of an Agent Communication Language to operate on such a context, and give an operational definition of the norms that are necessary to constrain the agents’ actions. In particular, we define the semantics of a library of communicative acts in terms of operations on agents’ social reality, more specifically on commitments, and regard norms as event-driven rules that, when fired by events happening in the system, create or modify a set of commitments. An interesting aspect of our proposal is that both the definition of the ACL and the definition of norms are based on the same notion of commitment. Therefore an agent capable of reasoning on commitments can reason both on the semantics of communicative acts and on the normative system