ools to support the process of analysis and design. This part relates to the areas of computer-aided design (CAD) and electronic design au- tomation (EDA). Having theory and tools available improves understanding, speeds up future design of similar systems and eases transfer of knowledge and experience to trainee designers. The history of the feedback amplifier offers us an excellent example as to the gains of a structured design process [Mind02]. First suggested by Harold Black, these ampli- fiers often showed undesired oscillatory behavior. Understanding and predicting this behavior has been the driver for Harry Nyquist and Hendrik Bode to develop the the- ory of feedback. This theory embeds feedback amplifiers within a global mathematical framework. It was a major step towards a better understanding and a more systematic design of feedback systems. Feedback theory has resulted in shorter design times by ensuring a priori the absence of oscillatory behavior. Nowadays, application of the theory is supported by numerous toolboxes. 1.1.4 Structured analysis Embedding knowledge within a global theoretical framework requires a structured and hierarchical approach towards analysis. Rather than having to reinvent the wheel time and again, theory and methods for modeling and analysis should apply to all systems exhibiting similar behavior. This implies a classification of systems according to their behavioral properties. It induces a tree-like hierarchy whereby each class is partitioned into further subclasses. This is accomplished by refining the behavioral properties that define (sub)class members. The different levels of hierarchy correspond to different levels of abstraction that either ignore or account for specific details of the system's behavior and/or implementation. Based on the set of properties that define a particular class of systems, methods for analysis -and hence design- are developed that apply to all systems of a that class. In Fig. 1.4 we consider the class of linear systems. Linear systems are defi