| 1 | === Base Template !RelationOfIndividualsToIndividuals === |
| 2 | |
| 3 | [[br]]This is a template for expressing that a relation relates individuals only. |
| 4 | [[br]]!RelationOfIndividualsToIndividuals(a) means that a is a relation of one of the subtypes of |
| 5 | !ClassOfRelationship, and that its domain and range (as determined by attributes according |
| 6 | to the entity type) are both first-order classes. |
| 7 | [[br]] |
| 8 | [[br]]Roles: |
| 9 | [[br]]1 hasRelation !ClassOfRelationship |
| 10 | |
| 11 | Axiom: |
| 12 | {{{ |
| 13 | RelationOfIndividualsToIndividuals(x) <-> |
| 14 | ClassOfRelationship(x) & |
| 15 | exists y1 exists y2(entityTriple(x, y1, y2) & |
| 16 | ClassOfIndividual(y1) & ClassOfIndividual(y2)) . |
| 17 | }}} |
| 18 | |
| 19 | NOTE The purpose of this unary template is in expressing a constraint on relations. The use of |
| 20 | the disjunctive entityTriple template (annex C.3) in the defining axiom means this template is not |
| 21 | suitable for introducing relations. |
| 22 | |
| 23 | NOTE The template language lacks the expressive power to fully capture the constraint intended |
| 24 | for this template. A full expression would require universal quantification, stating that for every |
| 25 | entity type to which the subject relation belongs, the attributes of the relation are first-order classes. |
| 26 | Universal statements are beyond the scope of template definitions (cf. 5.2, annex H). The template |
| 27 | still captures a useful approximation, because the intended constraint is satisfied given that the the |
| 28 | subject relation has only one pair of attributes (i.e., has unique domain and range). This requirement |
| 29 | is not captured in the ISO 15926-2 or template languages. |
| 30 | |
| 31 | EXAMPLE The expansion of !RelationOfIndividualsToIndividuals(Shaft Seal Connection) is a disjunctive statement that Shaft Seal Connection belongs to one of the subtypes of !ClassOfRelationship, with the appropriate attributes filled by first-order classes. |