Mobile Agent

Now a day's Heterogeneous wireless network is a promising field of research interest. Various challenges exist in this hybrid combination like load balancing, resource management and so on. In this paper we introduce a reliable load balancing architecture for heterogeneous wireless communications to ensure certain level of quality of service. To conquer the problem of centralized and distributed design, a semidistributed load balancing architecture for multiple access networks is introduced. In this grid based design multiple Load and Mobile Agent Management Units is incorporated. To prove the compactness of the design, integrated reliability, signalling overhead and total processing time is calculated. And finally simulation result shows that overall system performance is improved by enhancing reliability, reducing signalling overhead and processing time.

The aim of this paper is to present a distributed algorithm for big data classification, and its application for Magnetic Resonance Images (MRI) segmentation. We choose the well-known classification method which is the c-means method. The proposed method is introduced in order to perform a cognitive program which is assigned to be implemented on a parallel and distributed machine based on mobile agents. The main idea of the proposed algorithm is to execute the c-means classification procedure by the Mobile Classification Agents (Team Workers) on different nodes on their data at the same time and provide the results to their Mobile Host Agent (Team Leader) which computes the global results and orchestrates the classification until the convergence condition is achieved and the output segmented images will be provided from the Mobile Classification Agents. The data in our case are the big data MRI image of size (m × n) which is splitted into (m × n) elementary images one per mobile classification agent to perform the classification procedure. The experimental results show that the use of the distributed architecture improves significantly the big data segmentation efficiency.

We consider k mobile agents of limited energy that are initially located at vertices of an edge-weighted graph G and have to collectively deliver data from a source vertex s to a target vertex t. The data are to be collected by an agent reaching s, who can carry and then hand them over another agent etc., until some agent with the data reaches t. The data can be carried only over a fixed st path of G; each agent has an initial energy budget and each time it passes an edge, it consumes the edge's weight in energy units and stalls if its energy is not anymore sufficient to move. The main result of this paper is a 3-approximation polynomial time algorithm for the data delivery problem over a fixed st path in the graph, for identical initial energy budgets and at most one allowed data hand-over per agent.

We consider k mobile agents of limited energy that are initially located at vertices of an edge-weighted graph G and have to collectively deliver data from a source vertex s to a target vertex t. The data are to be collected by an agent reaching s, who can carry and then hand them over another agent etc., until some agent with the data reaches t. The data can be carried only over a fixed st path of G; each agent has an initial energy budget and each time it passes an edge, it consumes the edge's weight in energy units and stalls if its energy is not anymore sufficient to move. The main result of this paper is a 3-approximation polynomial time algorithm for the data delivery problem over a fixed st path in the graph, for identical initial energy budgets and at most one allowed data hand-over per agent.

Covert channel attacks utilize shared resources to indirectly transmit sensitive information to unauthorized parties. Current security mechanisms such as SELinux rely on tagging the filesystem with access control properties. However, such mechanisms do not provide strong protection against information laundering via covert channels. Colored Linux , an extension to SELinux, utilizes watermarking algorithms to "color" the contents of each file with their respective security classification to enhance resistance to information laundering attacks. In this paper, we propose a mobile agent-based approach to automate the process of detecting and coloring receptive hosts' filesystems and monitoring the colored filesystem for instances of potential information leakage. Implementation details and execution results are included to illustrate the merits of the proposed approach.

Growing recognition of the benefits of mobile agents in distributed systems, such as military C4ISR, has led to a proliferation of mobile agent systems. However, incompatibilities between proprietary systems prevent the greater potential benefits of ubiquitous mobile agent computing. In particular, agents cannot migrate to a host that runs a different mobile-agent system. Prior approaches to interoperability have tried to force agents to use a common API and so far none have succeeded. This goal led to our efforts to develop mechanisms that support runtime interoperability of mobile-agent systems. This paper describes the Grid Mobile-Agent System, which allows agents to migrate to different mobile-agent systems.

In the past few years, mobile agent (MA) paradigm has received a great deal of attention. While MAs have generated considerable excitement in the research community, they have not translated into a significant number of real-world applications. One of the main reasons for this is the ...

We propose in this paper a generic architecture to support, develop, manage, and interact with agentbased applications. In this context, we detail two main components of the architecture, namely: the AES (Agent Execution System) and the AEE (Agent Execution Environment). For both of them we describe their main concepts, data structures and interfaces. We also propose a set of characteristics that we believe will also be present in the next-generation AES, such as: independence between AES and AEE, ie, support to multi- ...

We present AntNet-QoS, a novel approach for Quality of Service routing which allows dynamic scheduling and forwarding among multiple packet classes in a differentiated service (DiffServ) network. The algorithm takes inspiration from the Ant Colony Optimization framework, and in particular from AntNet, which is an adaptive routing algorithm for best effort traffic. We show through simulations that the proposed scheme, which is purely proactive and does not use any form of bandwidth reservation, can provide very good performance in terms of end-to-end delay, throughput and jitter, and can obtain a good differentiation between classes.

Multilevel petrinets are proposed for facilitating flexible modeling and control of complicated dynamic processes. A metapetrinet is able not only to change the marking of a petrinet but also to reconfigure dynamically its structure. Each level of the metanet is an ordinary petrinet of some traditional type. A basic level petrinet simulates the process of some application. The second level, i.e. the metapetrinet, is used to simulate and help controlling the configuration change at the basic level. There is conformity between the places of the second level structure and places or transitions of the basic level structure. The main control rule is such that a certain place or transition is removed from the present configuration of the basic level if the corresponding place at the metalevel becomes empty. If at least one token appears to an empty metalevel place, then the originally defined corresponding basic level place or transition immediately is created back to the configuration. We also introduce multilevel metapetrinets where every upper level may change the configuration of the previous lower level. In such a case even a few levels with a simple structure are able to simulate quite complicated control processes at the basic level. We assert that metapetrinets offer more compact facilities to the models of complex dynamic processes than single level petrinets.

Nowadays the information contained in networks increases constantly, and the way to access this information and to gather important data to the users becomes a tedious task. The purpose of this work is to show the use of mobile agents to recover valuable information for the users they represent. In this work mobile agents are endowed with different strategies to retry information. Our approach is to obtain summaries by using the Transition Point technique (Punto de Transición) and to select those documents and sentences that have a high similarity with the user's requirements. To validate the summaries, the DUC 2002 and a statistical analysis are used. Moreover, the implementation of mobile agents is made in JADE.

Entity Resolution and Data Fusion are fundamental tasks in a Data Integration process. Unfortunately, these tasks cannot be completely addressed by purely automated methods and, then, a "humanin-the-loop" approach, i.e., the interaction with the Integration Designer has to be considered. In fact, the application goal can be relevant to reduce the complexity and the cost of the whole integration process. Moreover, the Entity Resolution and Data Fusion tasks are often considered consecutive and independent of each other: the output of the first step is used as input of the second one. In this paper, we will show how these tasks have not to be considered independent. In fact, the evaluation of data fusion results is fundamental for the Integration Designer to analyze, and eventually modify, the choices made during the Entity Resolution process. To show this, our highly scalable Entity Resolution tool, SparkER, will be extended with post-processing high-quality methods for matching. These methods will be integrated in the MOMIS Data Fusion system, extended as well with metrics for the evaluation of data fusion results.

The traditional learning paradigm invoving face-to-face interaction with students is shifting to highly data-intensive electronic learning with the advances in Information and Communication Technology. An important component of the e-learning process is the delivery of the learning contents to their intended audience over a network. A distributed learning system is dependent on the network for the efficient delivery of its contents to the user. However, as the demand of information provision and utilization increases on the Internet, the current information service provision and utilization methods are becoming increasingly inefficient. Although new technologies have been employed for efficient learning methodologies within the context of an e-learning environment, the overall efficiency of the learning system is dependent on the mode of distribution and utilization of its learning contents. It is therefore imperative to employ new techniques to meet the service demands of current and future elearning systems. In this paper, an architecture based on autonomous mobile agents creating a Faded Information Field is proposed. Unlike the centralized information distribution in a conventional e-learning system, the information is decentralized in the proposed architecture resulting in increased efficiency of the overall system for distribution and utilization of system learning contents efficiently and fairly. This architecture holds the potential to address the heterogeneous user requirements as well as the changing conditions of the underlying network.

We introduce an energy-efficient Cooperative target tracking framework for Wireless Sensor Networks (WSN). A Biological Independent Task Allocation (BITA) algorithm is presented to execute an application using a group of nodes. BITA is inspired from biological behaviours of differentiation in zygote formation. Simulation results show that BITA leads to improved network performance in terms of the number of served targets and service time compared with other commonly used algorithms.

We introduce an energy-efficient Cooperative target tracking framework for Wireless Sensor Networks (WSN). A Biological Independent Task Allocation (BITA) algorithm is presented to execute an application using a group of nodes. BITA is inspired from biological behaviours of differentiation in zygote formation. Simulation results show that BITA leads to improved network performance in terms of the number of served targets and service time compared with other commonly used algorithms.

This paper challenges the classical notion of undecidability in computation, demonstrating that problems traditionally considered "non-computable" collapse under structured recursion. By reframing recursion as inherently constrained rather than unbounded, we establish that fundamental problems like the Halting Problem, Post Correspondence Problem (PCP), and Busy Beaver function (BB(n)) are not truly undecidable but rather misrepresented due to incorrect recursion framing. This work presents an alternative model of recursion intelligence, positioning it as a foundational computational framework that supersedes classical assumptions of unbounded recursion. We provide formal proof derivations, empirical data, computational experiments, and structured falsifiability conditions to validate this claim.
Through large-scale simulations, we demonstrate that structured recursion intelligence drastically reduces undecidability spaces in practical computation. We introduce a bounding function F(n)=1.06×e0.99n\mathcal{F}(n) = 1.06 \times e^{0.99n} that accurately constrains BB(n) growth, contradicting claims of true non-computability. Additionally, our geometric transformation of PCP instances into constrained 3D recursive structures eliminates the need for infinite search, rendering the problem computationally tractable. Falsifiability conditions include demonstrating a BB(n) instance that exceeds our bounding function or identifying a PCP case that cannot be embedded into our structured 3D model. These findings suggest a paradigm shift in theoretical computer science, requiring a reevaluation of recursion-based complexity classes and computational limits.

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Mobile agents are an imminent technology for developing applications in mobile, distributed and pervasive computing. They offer a broad spectrum of features like autonomy; migrate to remote computers and process data to save remote connections. Mobile agents can be applied to a broad domain: network management, sensor network, grid computing, web services, and data mining. Numerous mobile agent systems have been developed, while some have been outdated and no longer in use others are in a continuous process of development, offering a variety of features. With the introduction of new computing platforms, to take advantage of mobile agent technology one must develop distributed applications that can cater to the needs. In this survey paper, we evaluate some of the existing mobile agent systems.

Programs based on code mobility, in particular on Mobile Agents, are an alternative approach to conventional distributed systems. Many aspects of Mobile Agent development have been addressed. In special, languages and environments to support code mobility and Mobile Agents implementation have been proposed. The testing activity though, has practically not been addressed so far. In this paper we present an approach and a tool named JaBUTi/MA to aid the test of Mobile Agents based on structural testing criteria. The structural test of Mobile Agents introduces a series of new difficulties, in particular the problem of how to collect execution data on such a distributed environment.

linux, 802.21, gestão de ligações Avanços recentes nas telecomunicações conduziram a uma combinação de várias interfaces de acesso à rede num único dispositivo. Os programas de gestão de ligações atuais lidam com as diferentes tecnologias individualmente, e baseiam a seleção da rede de acesso em parâmetros tais como a potência de sinal, ou taxa de transmissão máxima. Nem sempre estes mecanismos refletem a performance real de uma rede, levando a uma experiência de acesso fraca. Neste trabalho é implementada uma framework de gestão de ligações inovadora, baseada na norma IEEE 802.21. Esta norma disponibiliza mecanismos que facilitam e otimizam handovers entre diferentes tecnologias e a seleção de ligações através da troca de informações entre as entidades da rede e o terminal, incluindo informação de QoS, desempenho ou outras características. Além disso, a norma permite a gestão de dispositivos independentemente da tecnologia, através de uma interface uniformizada ao nível da camada de ligação de dados. Em virtude da extensão desta interface com mecanismos multi-camada, a nova framework possibilita a configuração asbtrata das interfaces de rede, incluindo a associação, configurações de segurança e endereçamento IP. O acesso a informação da rede capacita ainda os gestores de ligações para a realização de melhores decisões, tendo em conta o estado da rede e os requisitos das aplicações do terminal. Esta framework é integrada com as ferramentas e applets de configuração de rede do sistema operativo GNU/Linux, através da substituição transparente da aplicação NetworkManager. Em comparação, a nova framework apresenta overhead insignificante, uma quantidade de código inferior e melhor consumo de bateria, além de mecanismos otimizados para ligação oportunística.

Application of Mobile Agents in MANET is growing day by day to solve various network and user related problems in more efficient manner. However, before mobile agent's viable use in MANET, major performance issues such as reliability of Mobile Agent based System need to pay attention. Reliability of a mobile agent can be defined as its success ratio to fulfill its objective. MANET may have some malicious nodes which can affect the reliability of Mobile Agent based System (MAS). To overcome this issue, mobile agent should have some mechanism to find out the presence of these malicious nodes in MAS. Owner host node of Mobile Agent prepares the list of nodes the mobile agent required to visit to fulfill its task. This node list needs to be updated to remove the malicious nodes from the node list. Also, selection of suitable migration policy of agents is also necessary to ensure reliable Mobile Agent based System. This paper focuses on the enhancement of node list, selection of migration policy and MAS reliability based on reinforcement learning. This method helps mobile agent to learn about a preferred policy for selecting a suitable migration pattern and detecting malicious nodes present in the MANET. To measure the reliability of learning mobile agents, a Monte Carlo simulation based algorithm is proposed. Obtained results verifies that the learning of mobile agents contributes towards better reliability of MAS in suspicious MANET.

Mobile agent (MA) is a composition of software paradigm, having the capability to move from one host to another across dynamic network environment and execute task assigned by its user. Reliability is one of the most important issues in mobile agent-based system (MAS) which was addressed by many researchers. In this paper, we enhance the reliability in MAS with the support of intrusion detection system (IDS) and effective routing. Routing is an important process to find optimal path which improves network throughput and reliability. Collision-free (CF) -network graph exploration method is designed for identifying optimal path for MAs. Security is a crucial aspect due to various malicious node activities and must be considered while estimating reliability. In our process, HMAC-SHA1 algorithm is performed for detecting malicious agent and rule-based logic (RBL) is designed to identify malicious host. Further, we calculate reliability of MAS with respect to status of network and its condition which includes link connectivity and malicious node probability. Finally, we are simulating our performance by using various factors such as size of MAS, malicious ratio and number of mobile agents in MAS, etc. These factors are significant to show improved reliability of our proposed system.

Mobile agents are software entities consisting of code, data, state and itinerary that can migrate autonomously from host to host executing their code. Despite its benefits, security issues strongly restrict the use of code mobility. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems. In particular, collusion attacks have been barely studied in the literature. This paper presents a mechanism that avoids collusion attacks based on code passing. Our proposal is based on a Multi-Code agent, which contains a different variant of the code for each host. A Trusted Third Party is responsible for providing the information to extract its own variant to the hosts, and for taking trusted timestamps that will be used to verify time coherence.

Some of the most difficult questions to answer when designing a distributed application are related to mobility: what information to transfer between sites and when and how to transfer it. Networktransparent distribution, the property that a program's behavior is independent of how it is partitioned among sites, does not directly address these questions. Therefore we propose to extend all language entities with a network behavior that enables efficient distributed programming by giving the programmer a simple and predictable control over network communication patterns. In particular, we show how to give objects an arbitrary mobility behavior that is independent of the object's definition. In this way, the syntax and semantics of objects are the same regardless of whether they are used as stationary servers, mobile agents, or simply as caches. These ideas have been implemented in Distributed Oz, a concurrent object-oriented language that is state aware and has dataflow synchronization. We prove that the implementation of objects in Distributed Oz is network transparent. To satisfy the predictability condition, the implementation avoids forwarding chains through intermediate sites. The implementation is an extension to the publicly available DFKI Oz 2.0 system.

Recently, researchers have created many platforms and applications for mobile agents; however, current Agent-Oriented Software Engineering (AOSE) methodologies have yet not fully integrated the unique properties of these mobile agents. This paper attempts to bridge the gap between current AOSE methodologies and mobile agent systems by incorporating mobility into the established Multiagent Systems Engineering (MaSE) methodology. We accomplished this by adding a move command to the MaSE analysis models and then defined the required transformations to incorporate the required functionality into the design. Finally, we translated the design models into Java-based agents that operate within a mobile agent environment.

This paper analyzes the performance differences between static and mobile multiagent systems. To do so, we developed solutions to a distributed text search problem, each using a different approach to multiagent systems (static versus mobile) on an isolated test network. Changes were then made to the agent environment, various constraints applied, and the resulting effect on the systems measured. Each system was evaluated using a number of performance metrics to demonstrate the strengths and weaknesses of the respective approach.

This paper analyzes the performance differences between static and mobile multiagent systems. To do so, we developed solutions to a distributed text search problem, each using a different approach to multiagent systems (static versus mobile) on an isolated test network. Changes were then made to the agent environment, various constraints applied, and the resulting effect on the systems measured. Each system was evaluated using a number of performance metrics to demonstrate the strengths and weaknesses of the respective approach.

Two mobile agents, starting at arbitrary, possibly different times from arbitrary nodes of an unknown network, have to meet at some node. Agents move in synchronous rounds: in each round an agent can either stay at the current node or move to one of its neighbors. Agents have different labels which are positive integers. Each agent knows its own label, but not the label of the other agent. In traditional formulations of the rendezvous problem, meeting is accomplished when the agents get to the same node in the same round. We want to achieve a more demanding goal, called rendezvous with detection: agents must become aware that the meeting is accomplished, simultaneously declare this and stop. This awareness depends on how an agent can communicate to the other agent its presence at a node. We use two variations of the arguably weakest model of communication, called the beeping model, introduced in [8]. In each round an agent can either listen or beep. In the local beeping model, an agent hears a beep in a round if it listens in this round and if the other agent is at the same node and beeps. In the global beeping model, an agent hears a loud beep in a round if it listens in this round and if the other agent is at the same node and beeps, and it hears a soft beep in a round if it listens in this round and if the other agent is at some other node and beeps. We first present a deterministic algorithm of rendezvous with detection working, even for the local beeping model, in an arbitrary unknown network in time polynomial in the size of the network and in the length of the smaller label (i.e., in the logarithm of this label). However, in this algorithm, agents spend a lot of energy: the number of moves that an agent must make, is proportional to the time of rendezvous. It is thus natural to ask if bounded-energy agents, i.e., agents that can make at most c moves, for some integer c, can always achieve rendezvous with detection as well. This is impossible for some networks of unbounded size. Hence we rephrase the question: Can bounded-energy agents always achieve rendezvous with detection in boundedsize networks? We prove that the answer to this question is positive, even in the local beeping model but, perhaps surprisingly, this ability comes at a steep price of time: the meeting time of bounded-energy agents is exponentially larger than that of unrestricted agents. By contrast, we show an algorithm for rendezvous with detection in the global beeping model that works for bounded-energy agents (in bounded-size networks) as fast as for unrestricted agents.

Two mobile agents, starting from different nodes of an unknown network, have to meet at the same node. Agents move in synchronous rounds using a deterministic algorithm. Each agent has a different label, which it can use in the execution of the algorithm, but it does not know the label of the other agent. Agents do not know any bound on the size of the network. In each round an agent decides if it remains idle or if it wants to move to one of the adjacent nodes. Agents are subject to delay faults: if an agent incurs a fault in a given round, it remains in the current node, regardless of its decision. If it planned to move and the fault happened, the agent is aware of it. We consider three scenarios of fault distribution: random (independently in each round and for each agent with constant probability 0 < p < 1), unbounded adversarial (the adversary can delay an agent for an arbitrary finite number of consecutive rounds) and bounded adversarial (the adversary can delay an agent for at most c consecutive rounds, where c is unknown to the agents). The quality measure of a rendezvous algorithm is its cost, which is the total number of edge traversals. For random faults, we show an algorithm with cost polynomial in the size n of the network and polylogarithmic in the larger label L, which achieves rendezvous with very high probability in arbitrary networks. By contrast, for unbounded adversarial faults we show that rendezvous is not feasible, even in the class of rings. Under this scenario we give a rendezvous algorithm with cost O(nℓ), where ℓ is the smaller label, working in arbitrary trees, and we show that Ω(ℓ) is the lower bound on rendezvous cost, even for the two-node tree. For bounded adversarial faults, we give a rendezvous algorithm working for arbitrary networks, with cost polynomial in n, and logarithmic in the bound c and in the larger label L.

We establish a classification of decision problems that are to be solved by mobile agents operating in unlabeled graphs, using a deterministic protocol. The classification is with respect to the ability of a team of agents to solve the problem, possibly with the aid of additional information. In particular, our focus is on studying differences between the decidability of a decision problem by agents and its verifiability when a certificate for a positive answer is provided to the agents. We show that the class MAV of mobile agents verifiable problems is much wider than the class MAD of mobile agents decidable problems. Our main result shows that there exist natural MAV-complete problems: the most difficult problems in this class, to which all problems in MAV are reducible. Our construction of a MAV-complete problem involves two main ingredients in mobile agents computability: the topology of the quotient graph and the number of operating agents. Beyond the class MAV we show that, for a single agent, three natural oracles yield a strictly increasing chain of relative decidability classes.

We consider the task of rendezvous in networks modeled as undirected graphs. Two mobile agents with different labels, starting at different nodes of an anonymous graph, have to meet. This task has been considered in the literature under two alternative scenarios: weak and strong. Under the weak scenario, agents may meet either at a node or inside an edge. Under the strong scenario, they have to meet at a node, and they do not even notice meetings inside an edge. Rendezvous algorithms under the strong scenario are known for synchronous agents. For asynchronous agents, rendezvous under the strong scenario is impossible even in the two-node graph, and hence only algorithms under the weak scenario were constructed. In this paper we show that rendezvous under the strong scenario is possible for agents with asynchrony restricted in the following way: agents have the same measure of time but the adversary can impose, for each agent and each edge, the speed of traversing this edge by this agent. The speeds may be different for different edges and different agents but all traversals of a given edge by a given agent have to be at the same imposed speed. We construct a deterministic rendezvous algorithm for such agents, working in time polynomial in the size of the graph, in the length of the smaller label, and in the largest edge traversal time.

Two mobile agents (robots) have to meet in an a priori unknown bounded terrain modeled as a polygon, possibly with polygonal obstacles. Robots are modeled as points, and each of them is equipped with a compass. Compasses of robots may be incoherent. Robots construct their routes, but the actual walk of each robot is decided by the adversary that may, e.g., speed up or slow down the robot. We consider several scenarios, depending on three factors: (1) obstacles in the terrain are present, or not, (2) compasses of both robots agree, or not, (3) robots have or do not have a map of the terrain with their positions marked. The cost of a rendezvous algorithm is the worst-case sum of lengths of the robots' trajectories until their meeting. For each scenario we design a deterministic rendezvous algorithm and analyze its cost. We also prove lower bounds on the cost of any deterministic rendezvous algorithm in each case. For all scenarios these bounds are tight.

The aim of rendezvous in a graph is meeting of two mobile agents at some node of an unknown anonymous connected graph. In this paper, we focus on rendezvous in trees, and, analogously to the efforts that have been made for solving the exploration problem with compact automata, we study the size of memory of mobile agents that permits to solve the rendezvous problem deterministically. We assume that the agents are identical, and move in synchronous rounds. We first show that if the delay between the starting times of the agents is arbitrary, then the lower bound on memory required for rendezvous is Ω(log n) bits, even for the line of length n. This lower bound meets a previously known upper bound of O(log n) bits for rendezvous in arbitrary graphs of size at most n. Our main result is a proof that the amount of memory needed for rendezvous with simultaneous start depends essentially on the number of leaves of the tree, and is exponentially less impacted by the number n of nodes. Indeed, we present two identical agents with O(log + log log n) bits of memory that solve the rendezvous problem in all trees with at most n nodes and at most leaves. Hence, for the class of trees with polylogarithmically many leaves, there is an exponential gap in minimum memory size needed for rendezvous between the scenario with arbitrary delay and the scenario with delay zero. Moreover, we show that our upper bound is optimal by proving that Ω(log + log log n) bits of memory are required for rendezvous, even in the class of trees with degrees bounded by 3.

We investigate the Church-Kalmár-Kreisel-Turing Theses concerning theoretical (necessary) limitations of future computers and of deductive sciences, in view of recent results of classical general relativity theory. We argue that (i) there are several distinguished Church-Turing-type Theses (not only one) and (ii) validity of some of these theses depend on the background physical theory we choose to use. In particular, if we choose classical general relativity theory as our background theory, then the above mentioned limitations (predicted by these Theses) become no more necessary, hence certain forms of the Church-Turing Thesis cease to be valid (in general relativity). (For other choices of the background theory the answer might be different.) We also look at various "obstacles" to computing a non-recursive function (by relying on relativistic phenomena) published in the literature and show that they can be avoided (by improving the "design" of our future computer). We also ask ourselves, how all this reflects on the arithmetical hierarchy and the analytical hierarchy of uncomputable functions.

The intersection between Computational Intelligence and Agent technology opens new significant scenarios in many fields where the representation and management of complex systems play a fundamental role. In the formulation of Agent-based systems, the role of uncertainty is crucial for an efficient and coherent resolution of complex problems. Agents overcome classical programs thanks to their inner capabilities to be autonomous and to adapt their behavior with the changing of the environment where agents live and interact. This means that inevitably they meet uncertainty during their work, or in many cases, for the high complexity of the problem, the information they handle is (or needs to be) approximate. In recent years there has been a growing awareness that Computational Intelligence handling of uncertainty in agents is equally important as other features of agent paradigm. The objective of the proposed special issue is to highlight an ongoing research on computational intelligence agents and their applications on various domains. This special issue on computational intelligence agents receives thirteen papers, of which four papers have been accepted. This volume contains four papers that consider different aspects of perception based on the computational intelligent agents. The first paper HealthAgents: Distributed Multi-Agent Brain Tumour Diagnosis and Prognosis

The performance of the combined guard channels and mobile handoff call admission control is studied. If a handoff call arrives, and there are not enough channels for its service, it is queued in a finite buffer. Two customer types, narrowband (voice calls) and wideband (data, video and media) are considered. Matrix algorithmic techniques are used to solve the balance equations to calculate the different performance measures of the system. The results indicate that when handoff calls are queued, handoff call dropping is reduced for both types of calls and there is an increase in the bandwidth utilization. There is no noticeable change in the blocking probability of new calls. Increasing the size of the queue, led to further reduction in the handoff call dropping and increase in the bandwidth utilization.

Within the last two years, the Java technology has largely entered the world of element, network, and service management and has undoubtedly proven useful in combination with the SNMP framework for both manager and agent side developments. However, very few experiments have been made so far trying to provide an in depth integration of this technology within the TMN framework. In this paper we present a free software which offers a generic environment which provides a basis for reaching this integration. This environment, called J TMN , is composed of a set of Java soft- ware packages which enable both development and deployment of TMN compliant components. Not bound to any specific management platform and easily portable to any TMN system, its goal is to allow experimentation and deployment of more advanced features such as mobile agents, active network management, and advanced delegation in harmony with existing TMN approaches.

The paper presents "Any Input XML Output" (AIXO), a general and flexible software architecture for wrappers. The architecture has been designed to present data sources as collections of XML documents. The use of XSLT as extraction language permits extensive reuse of standards, tools and knowledge. A prototype developed in Java has been effectively proven in several case studies. The tool has also been successfully integrated as a wrapper service into BioAgent, a mobile agent middleware specialized for use in the molecular biology domain.

Hermes is a middleware system for design and execution of activity-based applications in distributed environments. It supports mobile computation as an application implementation strategy. While middleware for mobile computing has typically been developed to support physical and logical mobility, Hermes provides an integrated environment where application domain experts can focus on designing activity workflow and ignore the topological structure of the distributed environment. Generating mobile agents from a workflow specification is the responsibility of a context-aware compiler. Hermes is structured as a component-based, agent-oriented system with a 3-layer software architecture. It can be configured for specific application domains by adding domain-specific component libraries. The Hermes middleware layer, compilers, libraries, services and other developed tools together result in a very general programming environment, which has been validated in two quite disparate application domains, one in industrial control and the other in bioinformatics. In the industrial control domain, embedded systems with scarce computational resources control product lines. Mobile agents are used to trace products and support selfhealing. In the bionformatics domain, mobile agents are used to support data collection and service discovery, and to simulate biological system through autonomous components interactions.