This paper presents an approach to formal requirements speci cation of embedded systems. The speci c demands of a speci cation for command and control systems are addressed. The proposed method allows various views of a system, like conventional methods. The added value lies in the fact that the relationship between the views is speci ed formally, and consistency between views can be analyzed f...

This paper presents a Hoare-style logic for reasoning about the frequency response of control systems in the continuous-time domain. Two properties, the gain (amplitude) and phase shift, of a control system are considered. These properties are for a sinusoidal input of variable frequency. The logic operates over a simpli ed form of block diagram, including arbitrary transfer functions, feedback...

The COCOLOG (Conditional Observer and Controller Logic) system is a partially ordered family of rst order logical theories expressed in the typed rst order languages fL k ; k 0g describing the controlled evolution of the state of a given partially observed nite machine M. The initial theory of the system, denoted Th 0 , gives the theory of M with no data being given on the initial state. Later ...

This paper presents a Hoare-style logic for reasoning about the frequency response of control systems in the continuous-time domain. Two properties, the gain (amplitude) and phase shift, of a control system are considered. These properties are for a sinusoidal input of variable frequency. The logic operates over a simplified form of block diagram, including arbitrary transfer functions, feedbac...

Introduction Standardization has not always been a powerful force in electronics. However, recently the IEEE has adopted two standards in the area of digital interfacing, a field where great potential benefit exists in standardization. The first, IEEE STD-4%-19n, provides a standardized interface for programmable instruments and has been described in previous Spectrum articles. The second, IEEE...

Despite the enormous success that manual and automated refactoring has enjoyed during the last decade, we know little about the practice of refactoring. Understanding the refactoring practice is important for developers, refactoring tool builders, and researchers. Many previous approaches to study refactorings are based on comparing code snapshots, which is imprecise, incomplete, and does not a...

One of the most widespread framework for the management of access-control policies is Administrative Role Based Access Control (ARBAC). Several automated analysis techniques have been proposed to help maintaining desirable security properties of ARBAC policies. One limitation of many available techniques is that the sets of users and roles are bounded. In this paper, we propose a symbolic frame...