Control hierarchies in complex artifacts
Stephen H. Kendall, John R. Dale · 2023
When we examine the composition of complex artifacts, we are likely to see a hierarchical structure. The kind of hierarchy we find depends on the criteria we apply for the decomposition of the configuration under scrutiny. One criterion can be to consider the whole composed of parts that lend themselves for control by separate agents in charge of the design or maintenance of it. We will seek for such control units in the complex artifact. Hierarchies composed of control units tell us about the ways we can partially transform the artifact and how different designers may best distribute, among themselves, their design joint efforts. Hierarchies composed of control units we will call control hierarchies. Three kinds of control hierarchies are distinguished. The first, called assembly hierarchies , are commonly known and predominantly technical in nature. They tell us that a unit on a higher level of the hierarchy is composed of parts we find on the lower level. Control is one of assembly of smaller parts into a larger one and the process is a sequence of assemblies. In the other two control hierarchies the entities we find on a lower level do not assemble to form a higher-level unit. The relation between the levels is not one of assembly but of ‘dominance’ where the transformations on the lower level are constrained by the higher level. Of these two, one has to do with the control of physical elements and is called a dependency hierarchy . The other has to do with the control of spaces in which we distribute our physical parts and is called a territorial hierarchy . The paper also discusses the relation between these different hierarchical structures. It particularly touches upon the relation between dependency hierarchies and territorial hierarchies and considers how the same physical configuration can have different territorial interpretations.