Keijiro Araki

The state-based CCS semantics for concurrent Z specification

Presents a formal method which combines the Z notation and value-passing CCS (Calculus of Communicating Systems) for specifying concurrent systems. In order to provide a sound theoretical basis for the method, the state-based semantics for value-passing CCS is given. The main characteristic of the semantics is its ability in describing the evolution of processes and transitions of states simultaneously. We also present a Hennessy-Milner logic based on that semantics, which enables us to express properties such as liveness and safety ascribed both to states and to actions.

A general framework for debugging

The state of the art of debugging is examined. A debugged process model that serves as the basis of a general debugging framework is described. The relationship of the model to traditional debugging processes and support tools is discussed. A minimal set of requirements for a general debugging framework is described in terms of both the theory behind debugging methodologies and the support tools. An execution monitor, Eden, that serves as a debugging tool within this general framework is described.<<ETX>>

Specification slicing in formal methods of software development

Specifications are important in software development because a large percentage of the errors at implementation and test phases are traceable to a lack of precision of the specifications. Formal methods are studied and applied to produce clear specifications and argue about them rigorously. As formal methods may even increase the ratio of specification phase in the software life-cycle, it is necessary to be efficient in debugging, modification, and reuse of specifications to reduce cost of the whole software development process. In a large scale specification in particular, parts extracted from the specification are useful. We introduce here a specification slicing that supports debugging, modification and reuse of specifications. In this paper, we define specification slice as a part of a specification that defines or restricts values of a particular variable used in the specification. Attention is also directed to applications of specification slicing and support tools.<<ETX>>

Tasking communication deadlocks in concurrent Ada programs

Tasking communication deadlock is one of most typical synchronization errors in concurrent Ada programs. In this article, we specify four kinds of tasking communication deadlocks, i.e., Circular-entry-calling, Dependence-blocking, Termination-blocking, and Acceptance-blocking. We also discuss briefly how to detect such deadlocks.

Lamarckian evolution of associative memory

There has been a lot of research which applies evolutionary techniques to layered neural networks. However, their application to Hopfield neural networks remain few so far. We apply genetic algorithms to a fully connected Hopfield associative memory model. In an earlier paper, we reported that random weight matrices were evolved to store a number of patterns only by means of a simple genetic algorithm (A. Imada and K. Araki, 1995). We propose that the storage capacity can be enlarged by incorporating Lamarckian inheritance to the genetic algorithm.

NaraView: An Interactive 3D Visualization System for Parallelization of Programs

For effective use of parallelizing compilers, an interactive environment which allows users to find more parallelism is needed. As the first step towards building such an environment, we have developed a program visualization system named NaraView. In this paper, we describe two visualization methods in NaraView. One is Program Structure View which illustrates the hierarchical loop structure of a given program and suggests which parts of the program can be parallelized. Another is the Data Dependence View which visualizes each data dependence on every variable or array element which is accessed in a specific loop. By using these views, users can easily understand which part of the program can be parallelized further. We also show several examples to demonstrate the efficiency of these methods.

Random Perturbations to Hebbian Synapses of Associative Memory Using a Genetic Algorithm

We apply evolutionary algorithms to Hopfield model of associative memory. Previously we reported that a genetic algorithm using ternary chromosomes evolves the Hebb-rule associative memory to enhance its storage capacity by pruning some connections. This paper describes a genetic algorithm using real-encoded chromosomes which successfully evolves over-loaded Hebbian synaptic weights to function as an associative memory. The goal of this study is to shed new light on the analysis of the Hopfield model, which also enables us to use the model as more challenging test suite for evolutionary computations.

MDA and SOA approach to development of web application interface

A web application interface using the web service technology is required for enabling the interaction of various web applications on different platforms. In this paper, Model Driven Architecture (MDA) and Service Oriented Architecture (SOA) are combined as an approach using Service-Oriented Development Method (SOD-M) to develop of web application interfaces. The development process is initiated by describing the business process in the computation independent models (CIM). Afterward, the functionalities and processing systems in the Platform Independent Models (PIM), based on a business process and data types in the existing applications, are expressed. Model transformations are applied to generate the Web service interfaces in Web Service Desription Language (WSDL) and Web Service Business Process Execution Language (WS-BPEL) in the Platform Specific Models (PSM). For a case study, we illustrated a web interface application called Simpel as an interface between two existing applications in University of Lampung (Unila). This study shows how the proposed approach helps to develop web application that invokes web service to enable the interoperability of two existing application.

Design and evaluation of dynamic protocol selection architecture for reliable multicast

IP multicast is an effective technology for one-to-many and many-to-many communications. Multicast applications use UDP (User Datagram Protocol) as transport protocol and have responsibility for reliable communications. It is difficult to apply these implementations to other applications because implementations of multicast protocols have been pushed into application programs. We propose a reliable multicast architecture which extracts the process for reliability from multicast applications. We also designed a procedure for dynamic protocol selection which is the main part of our architecture. Thus, we show the effect of applying the dynamic protocol selection by using simulation and consider the overhead of dynamic protocol selection. We were able to achieve a high performance using this architecture as a result of these considerations.

Generating supportive hypotheses in introducing formal methods using a software processes improvement model

We are investigating the effective facilitation methodology for the introduction of formal methods into actual software developments. One of the important issues is how to define and develop an adequate development process with formal methods. In this paper, we discuss this issue from a view point of software process improvement using a standard development process model, CMMI-DEV, which is a compilation of best practices in software development. We expect using the standard process model as a reference can facilitate common understanding for the advantages of formal methods and the comparison between actual instances of software process with formal methods. This approach leads to the exploitation of knowledge and findings obtained in the successful cases. We generate supportive hypotheses in the effect of formal methods on software development processes by using the standard improvement model. Then, we weakly examine them with a combination of a small-scale process, which has a strong relation to the organization level process, and a model-oriented formal method, VDM.