The Semantic Access Control Model (SAC), built on the basis of separation of the authorization and access control management responsibilities, provides adequate solutions to the problems of access control in distributed and dynamic systems with heterogeneous security requirements. SAC is characterized by its flexibility for accommodating dissimilar security policies, but also by the ease of man...

The problem of specifying a radio-based railway level crossing control system is described. It is used within the DFG-supported Priority Programme \Software Speciication" as a comparison case study for a number of participating research projects and shall ooer realistic problems from the traac control systems domain. The remainder of the paper deals with the necessity to combine the beneets of ...

Fuzzy logic is a natural basis for modelling and solving problems involving imprecise knowledge and continuous systems. Unfortunately, fuzzy logic systems are invariably static (once created they do not change) and subjective (the creator imparts their beliefs on the system). In this paper we address the question of whether systems based on fuzzy logic can effectively adapt themselves to dynami...

In this paper we describe how an agent’s trust is a combination of the trust in the other agent and the trust in the control mechanisms. The trust an agent has in the control mechanisms depends on the agent’s understanding of the control mechanism. Therefore, we describe how this understanding can be analyzed using formal methods.

Agent planning programs are finite-state programs, possibly containing loops, whose atomic instructions consist of a guard, a maintenance goal, and an achievement goal, which act as precondition-invariance-postcondition assertions in program specification. The execution of such programs requires generating plans that meet the goals specified in the atomic instructions, while respecting the prog...

This paper describes the application of formal specification and verification methods to two microprocessor-based cryptographic devices: a “sman token” system that controls access to a network of workstations, and a message authentication device implementing the ANSI X9.9 message authentication standard. Formal specification and verification were found to be practical, cost-effective tools for ...