subtypedefined

Subtypedefined is a term used in theoretical computer science and knowledge engineering to describe the process or relationship by which a subtype is defined within a type system or ontology, such that the subtype is constrained by additional predicates while preserving the instances of the supertype. It emphasizes the explicit definition of the subtype through additional conditions that refine the set of valid instances.

Formally, subtypedefined can be represented as a refinement of a supertype S by a predicate Q, yielding a subtype T = { x in S | Q(x) }. The defining predicate Q adds new constraints without relaxing the base properties inherited from S. This perspective aligns with the idea of specialization or refinement, where every instance of T is also an instance of S, but not every instance of S is an instance of T. In practice, subtypedefined supports clear documentation of the exact criteria that distinguish the subtype from its parent type.

Examples appear across domains. In programming, a type Vehicle may define ElectricVehicle as a subtypedefined subtype with constraints such as batteryCapacity > 0 and chargingCapabilities = true. In data modeling, a table Person can give rise to a subtypedefined Employee defined by employmentStatus = 'active' and an employeeId field. In knowledge graphs, a class Mammal could be defined as a subtypedefined subclass of Animal with hasFur = true.

Subtypedefined supports precise data validation, type safety, and ontology design, though its use depends on rigorous constraint specification and may introduce additional complexity. See also subtype, refinement, specialization, and dependent types.