# G. Concepts and qualification

11 pages in this book.

| Page | What it is for |
|---|---|
| [Define necessary and sufficient conditions](/recipes/g-concepts/exact-definition/) | I want to derive a concept from sufficient conditions and check its necessary conditions. |
| [State only a necessary condition](/recipes/g-concepts/necessary-condition/) | I want to check a concept’s condition without turning it into a sufficient one. |
| [Classify with an exception](/recipes/g-concepts/defeasible-classification/) | I want to drop the ordinary qualification when an established exception applies. |
| [Treat a document as received](/recipes/g-concepts/deemed-receipt/) | I want to derive legal receipt from an established method of delivery. |
| [Forbid an incompatible combination](/recipes/g-concepts/non-deriving-constraint/) | I want to detect incompatibility of two qualifications without a hidden derivation of negation. |
| [Split a term’s meaning by the act’s purpose](/recipes/g-concepts/purpose-scope/) | I want to apply a definition only in an explicitly named domain. |
| [Assemble qualification from elements](/recipes/g-concepts/elements-of-offence/) | I want to derive the elements of an offence only when every element is established. |
| [Link a subtype and a temporal role](/recipes/g-concepts/role-and-subtype/) | I want to join subtype facts with supertype facts without turning a role into a permanent type. |
| [Choose the kind of a relation](/recipes/g-concepts/relation-kind/) | I want to name the nature of a fact without attributing evidential force to metadata. |
| [Distinguish an enum member from a data variant](/recipes/g-concepts/enum-and-variant/) | I want to keep enum identity and a variant’s payload. |
| [Declare relation functionality](/recipes/g-concepts/relation-key/) | I want to detect two values of one key while keeping both facts. |