Semantic Concepts: Relationships

Kees Woestenenk, 2012-07-19

Concepts are mutual related through Relationships:

Relationships are part of the formal definition of a Concept.

Specialization / Generalization

Specialization is a type-of hierarchy, where one Concept can be a type-of another Concept. A Concept that is a type-of another Concept is called a Subtype, and the other Concept Supertype. Specialization means that a Subtype is more specialized than its Supertype, or - stated otherwise - a Supertype is more general than its Subtypes. For example, a Family is a Subtype of an Organization. Specialization implies inheritance: a subtype inherits the Definition of its Supertype, and then modifies that Definition to become more specific. In that sense a Subtype is derived from its Supertype.

A Taxonomy is an example of a Specialization hierarchy, generally used as a classification structure for organisms. A Zebra is a type-of Mammal in a biological Taxonomy. Some Classification systems also make use of Specialization, although they are generally more View-oriented. For example: loggias, verandahs, conservatories, pavilions are types-of Covered spaces in the CI-SfB classification system

In SC all Concepts have at least one Supertype, except the Concept Concept that forms the top of the Specialization hierarchy. A Concept may have more than one Supertype, for example Concrete product in SC has Concrete and Product as Supertypes.

Composition / Aggregation

Composition is a part-of relationship, where one Concept can be a part-of another Concept. A Concept that is part-of another Concept is called a Component, or Part, or Element, or Member, and the other Concept the Aggregate, or Assembly or Composition.

In SC Composition relationships can be nested: a Component may be an Aggregate with other Components. For example a Door has a Locking system as a Component, and the Locking system has a Locking element as a Component.

Composition and Specialization

Both Composition and Specialization can be called Parent-Child relationships, or, more generally, Ancestor-Descendant relationships, and both Composition and Specialization have a tree-structure. The difference between Composition and Specialization is that a Composition is a has-a relationship without inheritence, whereas Specialization is a is-a relationship, where the child (Subtype) inherits the Definition of its Parent. For example, Ironmongery is a Collection of (mostly metal) articles, generally used for fixing. Apart for shops selling those articles they have no common Definition. As another example, Unit is a Concept with a special Definition in SC, Concepts derived from Unit are Subtypes.


Interaction is a relationship where one Concept acts-upon another Concept. The acting Concept is called the Actor, and the acted-upon Concept is called Subject. Acting may also be indicated as behaving: a Concept shows a certain behavior. For example, in SC an Interactivity of a Door is Access granting, which is a typical behavior of a Door.

Interaction and Composition

An Activity can also be a Component of a Concept. For example in SC, the Activity Door placing is a Component of a Door. This is because that Activity is actually part of the Door, causing that Door to be installed. On the other hand, the Activity of Access granting is behavior of the Door. Activity does not automatically involve Interactivity, sometimes it is, in the case of behavior, sometimes it is Composition, when it is part-of the coming-about of a Concept.


A Property relationship is the assignment of a Property (a type-of Concept) to another Concept. In this case Property is short for Property-of. A Property as a separate Concept may have a Value or a set of Values, when assigned to a Concept the Value(s) may change. In SC a Concept may have one or more assigned Properties, and a Property as a Concept may be assigned to one or more Concepts. For example, in SC the Property Chemical class has 3 Values: 'metal', 'non-metal' and 'semi-metal'; when assiged to the Concept Aluminium, the Value of the assigned Property is 'metal'.

Property - Measure - Unit - Value relationships

Property, Measure and Unit are distinct Concept types that are related through the Property - Measure - Unit - Value relationship. In this Relationship, the Property identifies the type-of property, the Measure identifies how a Value of the Property is measured, the Unit identifies which Unit is used in measuring the Value, and the Value contains the actual value content. For example, in SC Mass is a Property, Mass measure SI (kg) is one of its Measures and kg is the Unit. The Value of this Property is not determined, and depends of the Concept to which this Property is assigned.


A Usage relationship is the assignment of a Concept to other Concepts where it is used as part of the Definition. A Concept can be assigned to several other Concepts.


A Reference relationship is the assignment of an External Document to Concepts. An External Document can be assigned to several Concepts.