Modelling and implementation issues in circuit and network planning tools

This thesis consists of studies of modelling and implementation issues for planning tool development. In particularly it emphasizes issues that are relevant for practical, industrial use of mathematical models and algorithms. Using a circuit design and a network planning tool as concrete examples the thesis analyses the practical issues of the development and maintenance of such systems and, especially, how models and algorithms affect these. An important part of the thesis is observations of the changes in the software products over time and analysis what effect and requirements the evolution has for the models and algorithms The thesis deals with implementation in a wide sense. In addition to the issues of the implementation of a given algorithm this work discusses algorithm selection, development process, users' role, software evolution and how these affect each other. In particular the thesis tries to answer three questions: (i) What kind of models and algorithms to use in the tools? (ii) How to divide the work between the computer and the user? (iii) How to develop such tools? The main part of this research has been conducted using the participant observation research methodology by collecting and analysing experiences in the development of two commercial planning tool products. These results have been tied to the model of planning tool implementation that has been developed as part of this work. In particular the focus has been on how technology interacts with tasks, persons, and organizations. The results are also discussed within the context of established research disciplines such as operations research, software engineering, artificial intelligence, and problems solving environments. One finding of this work is the practical significance of simple algorithms and other building blocks that are easy to implement and enhance. This is often more important than high accuracy or strict optimality. The work also suggests a practical way to measure and compare the implementation complexity of algorithms. Another observation is how complex planning tasks should be divided between the computer and human expert. Examples how this is done using knowledge-technology, intelligent interfaces, and different kind of mathematical models are discussed. Practical issues in the development and evolution of algorithms and software are examined in case studies of routing algorithms and of a network visualization software component. These studies highlight the importance of the incremental development approach and discuss its implications to algorithms and software modules.