In this paper, we present an automatic implementation method by which executable communication programs in C can be generated from protocol specifications in LOTOS. The implementation method consists of two parts: 1) An implementation strategy and 2) a set of translation rules. The first part consists of the basic ideas on how to realize the primary mechanisms in LOTOS specifications. The second part formulates the implementation method by way of the translation rules based on the implementation strategy. The characteristics of our method can be summarized as follows: We formulate our implementation method by way of translation rules. These rules are defined topdown in the form of syntax-directed translation function. The mechanism for controlling concurrency and communication among the user processes corresponding to the processes in LOTOS specification is easily realized by using UNIX operating system functions. The translation rules have been implemented on the AS 3000 (SUN3) workstation. An application of this implementation method is demonstrated by a simplified token-ring-protocol.

In general, a two-dimensional display is defined by two orthogonal unit vectors. In developing the display, discriminant analysis has a shortcoming that the extracted axes are not orthogonal in general. First, in order to overcome the shortcoming, we propose discriminant analysis which provides an orthonormal system in the transformed space. The transformation preserves the discriminatory ability in terms of the Fisher criterion. Second, we present a necessary and sufficient condition that discriminant analysis in the original space provides an orthonormal system. Finally, we investigate the relationship between orthogonal discriminant analysis and the Karhunen-Loeve expansion in the original space.

To describe the state of visual communications in the U.S., two words come to mind: digital and anticipation. Although compressed, digital video has been used in teleconferencing systems for at least ten years, it is only recently that a broad consensus has developed among diverse industries anticipating business opportunities, value, or both in digital video. The drivers for this turning point are: advances in digital signal processing, continued improvement in the cost, complexity, and speed of VLSI, maturing international standards and their adoption by vendors and end users, and a seemingly insatiable consumer demand for greater diversity, accessibility, and control of communication systems.

This paper presents a destributed algorithm that uses weak copy consistency to create mutual exclusion in a distributed computer system. The weak copy consistency is deduced from the uncertainty of state which occurs due to the finite and unpredictable communication delays in a distributed environment. Also the method correlates outdated state information to current state. The average number of messages to enter critical section in the algorithm is n/2 to n messages where n is the number of sites. We show that the algorithm achieves mutual exclusion and the fairness and liveness of the algorithm is proven. We study the performance of the algorithm by simulation technique.

LOTOS is a language developed within ISO for the formal description of communication protocols and distributed systems. In LOTOS, requirements for a distributed system are called a "service specification". Each node exchanges synchronization messages to ensure the temporal ordering for the execution of events in a service specification. The actions of each node are described as a "protocol specification". This paper gives a survey for a method to derive protocol specifications from a service specification written in a LOTOS based language. In order to derive the protocol specifications, we make the syntax tree of a given service specification and give some attributes for each node in the tree. The protocol specifications are derived automatically by evaluating these attributes. The derived protocol specifications satisfy the given service specification. We also explain a LOTOS simulator for the execution of derived protocol specifications. The related works are also summarized.