资源受限的多Agent系统通信研究

在部分可观察环境中,Agent需要知识共享完成分布式合作.在资源受限的条件下,不加选择的通信会因为消耗有用的带宽产生性能瓶颈.因此,在资源受限的系统中需要在通信效用和通信代价之间进行适当的折衷.通过对无线网络通信方法的研究,基于信息冗余的思想讨论了多Agent系统的通信问题,提出了选择性信息交换算法,保证了Agent之间必要时的通信,以此来提高合作的效率.     

State Restoration in Systems of Communicating Processes

In systems of asynchronous processes using messagelists with SEND–RECEIVE primitives for interprocess communication recovery primitives are defined to perform state restoration: MARK saves a particular point in the execution of the program; RESTORE resets the system state to an earlier point (saved by MARK); and PURGE discards redundant information when it is no longer needed for possible state restoration.     

Testing Conditions for Communicating Stream X-machine Systems

X-machines were proposed by Holcombe as a possible specification language and since then a number of further investigations have demonstrated that the model is intuitive and easy to use. In particular, stream X-machines (SXM), a particular class of X-machines, have been found to be extremely useful in practice. Furthermore, a method of testing systems specified as SXMs exists and is proved to detect all faults of the implementation provided that the system meets certain “design for test conditions”. Recently, a system of communicating SXMs was introduced as a means of modelling parallel processing. This paper proves that each communicating machine component can be transformed in a straightforward manner so that the entire system will behave like a single stream X-machine - the equivalent SXM of the system. The paper goes on to investigate the applicability of the SXM testing method to a system of communicating SXMs and identifies a class of communicating SXMs for which the equivalent SXM of the system meets the “design for test conditions”. Received November 1999 / Accepted in revised form June 2001     

Expressing First-Order pi-Calculus in Higher-Order Calculus of Communicating Systems

In the study of process calculi, encoding between different calculi is an effective way to compare the expressive power of calculi and can shed light on the essence of where the difference lies. Thomsen and Sangiorgi have worked on the higher-order calculi (higher-order Calculus of Communicating Systems (CCS) and higher-orderπ-calculus, respectively) and the encoding from and to first-orderπ-calculus. However a fully abstract encoding of first-orderπ-calculus with higher-order CCS is not available up-tod...     

Modular Design of Real-Time Systems Using Hierarchical Communicating Real-time State Machines

This paper proposes a methodology for the development of distributed real-time systems. The methodology consists of the Hierarchical Communicating Real-Time State Machines (H-CRSM) modelling language, and the Violin toolset. H-CRSM combines Statecharts constructs with CSP-like timed communications. Violin provides a visual environment supporting in a seamless way all the life-cycle development phases of an H-CRSM system. Temporal validation rests on assertion checking during system simulation. Code generation is based on Java and a customizable runtime. The practical use of H-CRSM/Violin is shown by an example. A preliminary version of this paper appears in Proc. of Joint Modular Languages Conference (JMLC'2003), Klagenfurt, Austria, August 2003, LNCS 2789, Springer, pp. 110–121. Angelo Furfaro, Phd, is a computer science assistant professor at Unical, DEIS, teaching object-oriented programming. His research interests include: multiagent systems, Petri nets, parallel simulation, verification of time-dependent systems, distributed measurement systems. He is a member of ACM. Libero Nigro is a full professor of computer science at Unical, DEIS, where he teaches object-oriented programming, software engineering and real-time systems courses. He is the responsible of Software Engineering Laboratory (www.lis.deis.unical.it). His current research interests include: software engineering of time-dependent and distributed systems, real-time systems, Petri nets, modeling and parallel simulation of complex systems, distributed measurement systems. Prof. Nigro is a member of ACM and IEEE. Francesco Pupo, Phd, is a computer science assistant professor at Unical, DEIS, teaching introductory programming and computer architecture courses. His research interests include: Petri nets, discrete-event simulation, real-time systems, distributed measurement systems.     

Trust and Partial Typing in Open Systems of Mobile Agents

We present a partially typed semantics for Dπ, a distributed π-calculus. The semantics is designed for mobile agents in open distributed systems in which some sites may harbor malicious intentions. Nonetheless, the semantics guarantees traditional type-safety properties at good locations by using a mixture of static and dynamic type-checking. We show how the semantics can be extended to allow trust between sites, improving performance and expressiveness without compromising type safety.     

一个基于移动Agent的分布式入侵检测系统模型

本文分析了当前分布式入侵检测系统中存在的一般性缺陷,介绍了移动Agent的概念和优点,提出一种新的基于移动Agent的分布式入侵检测系统模型DIDSMA。DIDSMA采用分散的数据分析的机制,用静态代理作为主机监视器,用移动代理来收集数据、对数据进行集成和分析,并对入侵做出反应,解决了当前分布式入侵检测系统中存在的主要问题。     

Summarizing Vocabularies in the Global Semantic Web

In the Semantic Web, vocabularies are defined and shared among knowledge workers to describe linked data for scientific, industrial or daily life usage. With the rapid growth of online vocabularies, there is an emergent need for approaches helping users understand vocabularies quickly. In this paper, we study the summarization of vocabularies to help users understand vocabularies. Vocabulary summarization is based on the structural analysis and pragmatics statistics in the global Semantic Web. Local Bipa...     

Real-Time Search for Autonomous Agents and Multiagent Systems

Since real-time search provides an attractive framework for resource-bounded problem solving, this paper extends the framework for autonomous agents and for a multiagent world. To adaptively control search processes, we propose -search which allows suboptimal solutions with error, and -search which balances the tradeoff between exploration and exploitation. We then consider search in uncertain situations, where the goal may change during the course of the search, and propose a moving target search (MTS) algorithm. We also investigate real-time bidirectional search (RTBS) algorithms, where two problem solvers cooperatively achieve a shared goal. Finally, we introduce a new problem solving paradigm, called organizational problem solving, for multiagent systems.     

基于自适应Agent的入侵检测系统研究

探讨了利用入侵检测自治代理和自适应模型生成相结合的系统方案，提出了Agent逻辑连接的方法，有效降低了系统的配置难度，同时提高了系统运行的可靠性和容错性。     

Stochastic Model for Communicating Retrial Queuing Systems with Cyclic Control in Random Environment1

The cybernetic approach is used to develop a mathematical model for communicating queuing systems. Conflicting input flows of the first queuing system and one of the input flows of the second queuing system are formed in a synchronous Markov random environment with a finite number of states. Another input flow of the second queuing system consists of retrials arriving from the first queuing system. The transition of a customer from the first queuing system to the second one takes a random amount of time. Servicing is performed by a cyclic algorithm with fixed duration.     

Predicting Interactions Between Agents in Agent-Based Modeling and Simulation of Sociotechnical Systems

Agent-based modeling and simulation are a valuable research tools for the analysis of dynamic and emergent phenomena of large-scale complex sociotechnical systems. The dynamic behavior of such systems includes both the individual behavior of heterogeneous agents within the system and the emergent behavior arising from interactions between agents; both must be accurately modeled and efficiently executed in simulations. This paper provides a timing and prediction mechanism for the accurate modeling of interactions among agents, correspondingly increasing the computational efficiency of agent-based simulations. A method for assessing the accuracy of interaction prediction methods is described based on signal detection theory. An intelligent interaction timing agent framework that uses a neural network to predict the timing of interactions between heterogeneous agents is presented; this framework dramatically improves the accuracy of interaction timing without requiring detailed scenario-specific modeling efforts for each simulation configuration.      

一种Internet移动代理系统的黄页服务模型

提出了一种基于信度推理网络的移动代理系统黄页服务模型,为自主迁移的移动代理提供迁移决策支持。与现有的移动代理系统黄页服务模型相比,该模型较好地解决了信息局部性和信息更新的问题,其结构具有良好的可扩展性和灵活性,能更好地适应Ｉｎｔｅｒｎｅｔ动态的网络环境。     

An Engineering Approach to Cooperating Agents for Distributed Information Systems

This paper presents a multi-agent model of a distributed information system, using what is described as an engineering approach to real world application environment. The objective is to define, using proven ideas in the industrial context, the agent-based behaviour of the distributed system, which must operate correctly and effectively in an error-prone environment. Issues such as stability, robustness and scalability have also been addressed, along with some new ideas on a high-level communication strategies, as distinct from protocol-based communications. The work is being carried out under the DREAM theme at Keele, an earlier version of the approach having been successfully applied to agent-based manufacturing in an international project called HMS, in which some of the world’s major manufacturing industries participated.     

Optimizing the Scalability of Network Intrusion Detection Systems Using Mobile Agents

Modern Intrusion Detection Systems (IDSs) are distributed real-time systems that detect unauthorized use or attacks upon an organization's network and/or hosts. The components of most distributed IDSs are arranged in a hierarchical tree structure, where the sensor nodes pass information to the analyzer nodes. Optimal placement of the analyzer nodes results in an improved response time for the IDS, and isolation of attacks within the IDS network. Since the network topology and workload are constantly changing, we are able to maintain near-optimal placement of the analyzer nodes by instantiating them as mobile agents. The analyzer nodes may then relocate, reproduce or be deleted as necessary. Such flexibility improves the response times and the stability of an IDS. The movement of the analyzer nodes also offers some protection against denial-of-service attacks, since secure analyzer nodes will be relocated to take over some of the functionality of the host under attack.     

Controlled Vocabularies in OODBs: Modeling Issues and Implementation

A major problem that arises in many large application domains is the discrepancy among terminologies of different information systems. The terms used by the information systems of one organization may not agree with the terms used by another organization even when they are in the same domain. Such a situation clearly impedes communication and the sharing of information, and decreases the efficiency of doing business. Problems of this nature can be overcome using a controlled vocabulary (CV), a system of concepts that consolidates and unifies the terminologies of a domain. However, CVs are large and complex and difficult to comprehend. This paper presents a methodology for representing a semantic network-based CV as an object-oriented database (OODB). We call such a representation an Object-Oriented Vocabulary Repository (OOVR). The methodology is based on a structural analysis and partitioning of the source CV. The representation of a CV as an OOVR offers both the level of support typical of database management systems and an abstract view which promotes comprehension of the CV's structure and content. After discussing the theoretical aspects of the methodology, we apply it to the MED and InterMED, two existing CVs from the medical field. A program, called the OOVR Generator, for automatically carrying out our methodology is described. Both the MED-OOVR and the InterMED-OOVR have been created using the OOVR Generator, and each exists on top of ONTOS, a commercial OODBMS. The OOVR derived from the InterMED is presently available on the Web.