| | 110 | |
| | 111 | ''Figure 2: The `owl:Class` `Specialization`, the `owl:ObjectProperty`s `hasSubclass`[[BR]]and `hasSuperclass` (solid line), their inverse `owl:ObjectProperty`s `isSubclassIn`[[BR]]and `isSuperclassIn` (dashed line) respectively -- and the `owl:propertychain`[[BR]]`isSubclassIn-o-hasSuperclass` (in red).'' |
| | 112 | |
| | 113 | }}} |
| | 114 | |
| | 115 | |
| | 116 | == ISO 15926-2:2003 chained roles == |
| | 117 | |
| | 118 | The file http://rds.posccaesar.org/2008/09/OWL/ISO-15926-2_2003_chainedRoles defines a series of `owl:propertyChain`s. Property chains are the "owl-equvialent" to the mathematical [http://en.wikipedia.org/wiki/Relation_composition composition of relations]. |
| | 119 | |
| | 120 | The (binary) relations defined in ISO-15926 are ''reified'', meaning that they are represented as entities with two attributes, e.g., the `COMPOSITION_OF_INDIVIDUAL` entity has two attributes: `part` and `whole`. In OWL the common way of representing relations is by means of binary properties, e.g., `hasPart` having "wholes" as domain and "parts" as range. This is equivalent to a binary logical predicate [[LatexEquation(hasPart(x, y))]] which is true only if [[LatexEquation(y)]] is a part of [[LatexEquation(x)]]. The property chain construct in OWL allows for an elegant definition of the more "OWL friendly" binary properties from the reified relations. |
| | 121 | __Example__: Specializations of classes in ISO 15926 are represented using the reified entity `SPECIALIZATION`. `SPECIALIZATION` has two attributes `subclass` and `superclass`. In the [http://rds.posccaesar.org/2008/02/OWL/ISO-15926-2_2003 OWL representation of ISO 15926-2] this becomes the `owl:Class` `Specialization` and two `owl:ObjectProperty`s `hasSubclass` and `hasSuperclass` where the domain of the two properties is the class `Specialization`. (Read more on the OWL representation here). In OWL specialization is represented using `rdsf:subClassOf`. This relation can be mimiced by a property chain of `isSubclassIn` (the inverse property of `hasSubclass`) and `hasSuperclass`. This property chain is defined in [http://rds.posccaesar.org/2008/09/OWL/ISO-15926-2_2003_chainedRoles ISO-15926-2_2003_chainedRoles] and is called `isSubclassIn-o-hasSuperclass`. See Figure 2 for an illustration of this example. |
| | 122 | |
