Integral Logistics Management — Operations Management and Supply Chain Management Within and Across Companies

20.2.3 Whole-Part Hierarchy, and Specialization Hierarchy

Intended learning outcomes: Differentiate between the component hierarchy, or whole-part hierarchy, and the specialization hierarchy.

Through hierarchy creation, in a view of the information system, “lower” items belonging to a “higher” item are grouped/classified.

Hierarchy creation is a very important construct in modeling. It pervades and characterizes modeling, for which reason it can actually be called a dimension of modeling. Through hier­archy creation, elements belonging together are arranged, grouped, or classified in sets. The following three types of semantics in hierarchy creation are observed frequently in practice: 

  • Component hierarchy, or whole-part hierarchy
  • Specialization hierarchy
  • Association hierarchy, or determination hierarchy

In the component hierarchy, or whole–part hierarchy, a hierarchically superior element G is composed of (consists of) elements T1, T2, T3, …

In reverse order, each of the hierarchically subordinate elements T1, T2, T3, … is a part or component of a superior element G. Figure illustrates the semantics.

Fig.       Component hierarchy, or wholepart hierarchy.

Examples of component hierarchies in the material world are:

  • A bicycle (as a whole) with its components: handlebars, frame, and wheels
  • A transport (as a whole) with its phases: load, transport, and unload.

Examples of component hierarchies in information systems are: 

  • A system with its subsystems
  • An object with its components
  • A process with its subprocesses
  • A function with its subfunctions
  • A task with its subtasks.

The dimension of the principle of proceeding “from the general to the particular” in systems engineering (Section 19.1.1) and in different modeling tool sets corresponds to a component hierarchy. 

In a specialization hierarchy the elements S1, S2, S3, … represent special manifestations of the superior element G. In other words, each of the elements S1, S2, S3, … is a (special) G.

In reverse order, the hierarchically superior element G is a generalization of all subordinate elements S1, S2, S3, … In other words, an element G can be an element S1 or an element S2 or an element S3, and so on. Figure illustrates the semantics.

Fig.       Specialization hierarchy.

Examples of specialization hierarchies in the company environment are  

  • Employees of a company (generalization) with the various mani­festations “salaried employee,” “blue-collar worker,” and “trainee.”
  • A shipping service (generalization) with its various options: “express,” “normal,” or “lowest-cost” processing. 

Examples of specialization hierarchies in the modeling of information systems are

  • An object with its specialized manifestations
  • A process with various processing options

Continuation in next subsection (20.2.3b).

Course section 20.2: Subsections and their intended learning outcomes