Some Properties of Complete Functional Elements

Many of the properties of functional elements discussed in this chapter were developed in earlier publications, in particular in [1]. However, for various reasons, the emphasis there was on functional elements as representations of the functionality of plants, and consequently the development was based on maximal elements. Here, we are focused on the initial stage of design based on the stakeholder requirements - design in the functional domain - and so we are primarily concerned with functional elements as representations of these requirements. This is reflected in the next two sections. 

The important point here is that, as we add functional elements in the decomposition process, the resulting elements are complete with respect to a larger and larger subset of the stakeholder requirements, until we arrive at an element that is complete with regard to the whole set of stakeholder requirements. But what element we add in order to cover one or more specific stakeholder requirements is up to us there will in general be several different functionalities that will satisfy the same set of requirements. And the effect of adding a particular 

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