TAMAP: a new trust-based approach for mobile agent protection

Human activities are increasingly based on the use of distant resources and services, and on the interaction between remotely located parties that may know little about each other. Mobile agents are the most suited technology. They must therefore be prepared to execute on different hosts with various environmental security conditions. This paper introduces a trust-based mechanism to improve the security of mobile agents against malicious hosts and to allow their execution in various environments. It is based on the dynamic interaction between the agent and the host. Information collected during the interaction enables generation of an environment key. This key allows then to deduce the host’s trust degree and permits the mobile agent to adapt its execution accordingly to the host trustworthiness, its behavior history and the provided Quality of Service (QoS). An adaptive mobile agent architecture is therefore proposed. It endows the mobile agent with the ability to react with an unexpected behavior.     

A purely object-oriented approach for rule-based paradigms

In this paper, I describe an approach for rule-based systems exploiting a purely object-oriented approach. The innovative idea is to consider a new kind of relation between knowledge objects which are believed to model implication relations of production rules. A knowledge base consisting of such objects can be conveniently represented as a Marker Propagating Graph (MPG), which provides rule-based-like representation features. The inference is seen as a marking propagation through the graph. This approach preserves the best of both the object orientation features and expert system functionality. This experimental study concerns the design and the implementation of a medical system for automatic interpretation of biological tests in Preventive Medicine Centers. Because the use of such a system is planned for many years, the possibilities for its future extensions are seriously considered. This would not be possible without a good appreciation of object orientation features.     

An actor model for rule-based systems

Our research originates from a study of the possibilities of integrating rules and objects in knowledge-based systems. In the present work, we are interested in the interactionist perspective of an object. The stepwise reasoning of a diagnostic expert system, possibly involving subgoaling and interactions with the environment, can be easily codified by means of production rules over proposition literals. This set of rules can be graphically represented in a network manner denoting the relations between the rules. The individual nodes in the network can be expressed by means of autonomous objects and their relations, interpreted as possible communications between them. The objects are given a structure and a proper behaviour and cooperate for performing logical reasoning by means of forward and backward chaining inference processes. Therefore, designing this system implies addressing several basic issues such as inter-object communications and their synchronization. The problem here is not necessarily to develop a great intelligence locally but to develop strong networks of good communicators. This approach belongs to the interactionist representation current, where objects are called actors. In principle, the actors may carry out computation in parallel and provide a conceptual foundation for massively concurrent object-oriented paradigms. From this point of view, a system allowing for the simultaneous investigation of several rules and premises in the forward or the backward chaining would be significantly more efficient.