Concept · dictionary entry

Invariant

A property that is required to hold across a class of permitted transformations.

Definition

An invariant is a property required to hold across a class of permitted transformations of a system. Invariants may be scoped to identity (what makes an entity the same entity), to evidence (what evidence must persist), to authority (what an entity may conclude), or to boundary (what regions of the system may not be crossed). Every invariant is stated explicitly.

Formal reference

Governed Relational Geometry: A Formal Model for Evidence, Context and Valid Transformation — §4

Related concepts

• valid transformation
• authority boundary

Demonstrations

• Chamber scenario scenario-1
• Chamber scenario scenario-2
• Chamber scenario scenario-3
• Chamber scenario scenario-4

Limitations

• An invariant that no transformation would ever violate is not informative
• Invariants themselves may be revised — the revision must be recorded