Structure
The arrangement and relationships between components — how the system is organized. Structure enables and constrains what the system can do.
Formal Definitions
Mobus & Kalton (2015):
“N is a graph with vertices (components) and directed edges (links): N_{i,l} = ⟨C_{i,l}, L_{i,l}⟩”
(Principles of Systems Science, Section 4.3, Eq. 4.4)
“The structural skeleton established thus far has only explicated the organization of subsystems (complex components) and sub-subsystems (complex or atomic components) in a hierarchy of scale.”
(Section 4.3)
Bunge (1979):
“The A-structure (or organization) of σ at time t is the set of relations, in particular bonds, among the components of σ, and among them and the things in the environment of σ.”
(A World of Systems, Definition 1.2, Chapter 1)
“A connection is a special type of relation that makes a difference.”
(Chapter 1, p. 6)
Bunge distinguishes structure (S) from mere relations: structure includes only those bonds that are functionally significant.
Synthesis
Mobus defines structure as graph-theoretic organization — nodes (components) and edges (links) with hierarchical nesting. Bunge defines structure as the time-parameterized set of all functionally significant relations (bonds) among components and between components and environment. Both emphasize relational organization, but Bunge makes an important distinction: not all relations are structural — only those that make a causal difference.
Key Insight
Structure constrains function. The same components arranged differently produce different behaviors. This is why organizational charts matter — the pattern of connections shapes what’s possible.
Explore Further
- Structure, function, and history — Zwick’s analytical triad
- Five aspects of system knowledge — Structure as essential
- Ontological categories — Structure alongside function