June 1987 - Vol. 30 No. 6
Features
Electronic markets and electronic hierarchies
By reducing the costs of coordination, information technology will lead to an overall shift toward proportionately more use of markets—rather than hierarchies—to coordinate economic activity.
Power over users: its exercise by system professionals
Analysis and awareness of the types of power that IS professionals exercise over users can improve the productivity of both parties.
Systems analysis: a systemic analysis of a conceptual model
Adopting an appropriate model for systems analysis, by avoiding a narrow focus on the requirements specification and increasing the use of the systems analyst's knowledge base, may lead to better software development and improved system life-cycle management.
A versatile data structure for edge-oriented graph algorithms
An abstract graph module that allows for easy and secure programming of a great number of graph algorithms is implemented by symmetrically stored forward and backward adjacency lists, thus supporting edge-oriented traversals of general directed and undirected graphs.
Arithmetic coding for data compression
The state of the art in data compression is arithmetic coding, not the better-known Huffman method. Arithmetic coding gives greater compression, is faster for adaptive models, and clearly separates the model from the channel encoding.
Rule-based versus structure-based models for explaining and generating expert behavior
Flexible representations are required in order to understand and generate expert behavior. Although production rules with quantifiers can encode experiential knowledge, they often have assumptions implicit in them, making them brittle in problem scenarios where these assumptions do not hold. Qualitative models achieve flexibility by representing the domain entities and their interrelationships explicitly. However, in problem domains where assumptions underlying such models change periodically, it is necessary to be able to synthesize and maintain qualitative models in response to the changing assumptions. In this paper we argue for a representation that contains partial model components that are synthesized into qualitative models containing entities and relationships relevant to the domain. The model components can be replaced and rearranged in response to changes in the task environment. We have found this "model constructor" to be useful in synthesizing models that explain and generate expert behavior, and have explored its ability to support decision making in the problem domain of business resource planning, where reasoning is based on models that evolve in response to changing external conditions or internal policies.
Relationships between selected organizational factors and systems development
Three organizational variables influence the quality of the system development process: available resources (both human and financial), external influences on the development process, and the project team's exposure to information systems. Public information and interviews with systems managers from 28 large private firms yielded data about the organizational variables. Systems project group members completed questionnaires concerning the system development process. The results indicate that human resources affect the development process positively, but increased financial resources are related to team disagreement. The degree of external influence on the system development effort needs to be carefully monitored and controlled. Systems exposure in the firm allows an increase in the degree of awareness among project group members about the different problems encountered by users and systems staff.
