| Publisher: | Ontopia AS |
|---|---|
| PSI: | http://psi.ontopia.net/ontology/is-symmetric |
| Status: | Stable |
| PSI set: | Ontopoly meta-ontology |
| Type: | Association type |
Unary association used to mark association types as being symmetrical. Symmetric associations are associations like friend-of or neighbour-of where X friend-of Y implies that also Y friend-of X. In Topic Maps these are implemented as binary associations where the same role type is played by both topics, as follows:
friend-of(X : friend, Y : friend)This way, the association only has to be stated once to be applicable in both directions. However, Ontopoly treats association types with just a single role type as unary associations. Therefore, it's necessary to state explicitly that these association types are symmetric, and that is done with this unary association.
Usage:
on:is-symmetric(friend-of : on:field-type)