Naoki Shiba

A HIERARCHY OF DECISION MAKING CONCEPTS: CONCEPTUAL FOUNDATION OF DECISION SUPPORT SYSTEMS

This paper describes the concepts related to decision making within a unified framework from the point of view of general systems theory. Decision support systems (DSS) are computer systems intended to support the decision making process. Current DSSs are, however, mainly designed to provide a direct support for a decision problem only when its model is numerically well formulated. We believe that a computer should and can provide the decision making process with more active supports. Therefore, ii is necessary to have an integrated image of the relationships among the concepts of decision making for the construction of this kind of systems. We start from an abstract general input-output model and finally reach a concrete solution finding model introducing new concepts step by step. The assertion of this paper is that the various concepts related lo decision making can be arranged as a hierarchy in this way

An implementation of unified programming on actDSS

Abstract A unified programming environment is implemented on our DSS generator, called actDSS, which is a general platform for constructing intelligent specific systems. The architecture of the implemented unified programming is a hierarchical connection of a numerical solver and a non-numerical evaluator. The former produces an optimum solution of a problem and the latter evaluates the solution heuristically, controlling the total model that encompasses the former by modifying the constraint and the parameter value. A job assignment problem is used as a demonstration of the architecture, which is formulated as a mixed integer programming problem. In this paper, a general scheme of the unified programming is introduced. Its feasibility on actDSS is demonstrated and finally we discuss how the implementation was possible in the system.

MODEL INTEGRATION FOR MANAGERIAL DECISION SUPPORT USING A MODEL DESCRIPTION LANGUAGE WITH A FORMAL SEMANTICS

Fundamental concepts are presented for realizing hierarchical bottom-up model building in managerial decisions using a model description language with formal semantics. Two types of model representation are introduced. One is a model description, which is a representation of the internal structure of models. The other is an executable module, which is used in model integration context, and is the conceptualization of a model as an input-output functional system. The distinction and relationship between these two types of representation are discussed formally and strictly in the model theoretic way. Finally, a prototype system of a model integration environment will be implemented based on these concepts.

MODEL MANAGEMENT FOR HIERARCHICALLY STRUCTURED MODELS AND ITS APPLICATION

The implementation of a model management system for hierarchically structured models, named DIALOGO, is discussed. In the authors model management concept the structure of models is defined with the mathematical formulation of the hierarchical structure based on the framework of the theory of hierarchical, multilevel systems in the mathematical general systems theory by Mesarovic and Takahara. Assuming that model components are given as dynamical input/output systems, the mechanism which enables us to realize simulation with hierarchical structured models as a whole is discussed. The method to execute the simulation by converting a hierarchically structured model into a flat network of model components is presented. The implemented platform is applied to a typical problem in global issues, the Nile River basin problematique, in order to demonstrate effectiveness of the concept.

DSS as an application of general systems theory

This paper examines how an object called a decision support system (DSS) is a system from the point of view of GST (general systems theory) and how GST is related with the development of DSS in a positive way. Since a DSS is a complicated system, it cannot be described by one model. We will proceed the consideration in the following different levels: functional level, structural level, process level and physical level. We will show that on each level GST provides a useful framework to deal with a DSS and the general formulation by GST directs what is to be done in the development of DSS. On the progress of the development we have found GST can help us with conceptualizing a DSS which is most important in finding a correct research direction. The presented models are the basic framework of our current system, a product of GST.

Systems Theory and Systems Implementation: Case of DSS

A DSS (decision support system) is a CBIS (computer based information system) designed to support a rational decision making for a semi-structured problem. In order to make a rational decision we need models for a problem. A DSS can be distinguished from other CBIS by the fact that a model plays an essential part in it.

DEPENDENCE STRUCTURE— DEPENDENCE AS A BINARY RELATION

In systems theory, we often use the concept of dependence. There are several research to construct a unified framework for dependence. Mainly, the concept of dependence is defined with a dais of subsets, where the concept of algebraic closure systems is often used. In this paper, we define dependence as a binary relation, which we call dependence structure, and develop a similar argument as for the dependence with a class of subsets. And we will clarify a relationship between dependence structure and the usual concept of dependence. We also show what conditions assure the existence of a basis for a dependence structure. The concept of functional dependence in database theory can be represented as a dependence structure and we will show that a key for a relational scheme is a basis for the dependence structure.

Application of Intelligent Worldwide DSS to Optimization Problems

Appearance of the web technology begins to take effect in DSSs. In this paper we consider a new architecture of DSS in which we can utilize the worldwide information resources by web technology. For an application of worldwide DSS, we illustrate an intelligent worldwide DSS implemented in order to solve optirnization problems.