ontologyprotege4

Can individual connect to class with object property on Protege?

is there any way individual (instance) connect to class with object property? For example, individual in this case is module name: Web Programming. Object property : isClassified. Class: Network.

I've tried to define Web Programming as class, and it works because the domain and range are both classes. Same goes if I define both Web Programming & Network as individuals, it works. If the domain is a class and the range is individual, it still works. But what if the domain is individual and the range is class? Is there any way I can connect it with object property: isClassifiedIn?

Solution

  • Protégé is an OWL 2 DL editor (since version 4). In OWL 2 DL, an individual cannot be a class, and an object property must relate individuals to individuals only. So what you want cannot be expressed in the way you formulate it. However, you could do two things:

    1. use an annotation property instead of an object property. This may not be ideal because an OWL DL reasoner must ignore annotation properties in the reasoning process. They are just that: annotations, similar to comments in a programming code.
    2. relate the individual to another individual that has the same name as the class. Let me give details about this.

    In OWL 2 DL, although it is not possible for individuals to be classes, it is possible for individual names to be class names at the same time. For instance, one can say (in Turtle syntax):

    ex:Module  a  owl:Class .
ex:Network  a  owl:Class, owl:Thing .
ex:isClassified  a  owl:ObjectProperty .
ex:webProgramming  a  ex:Module;
    ex:isClassified  ex:Network .

    Note that ex:webProgramming here is not related to a class. It is related to an individual of type owl:Thing. This individual has nothing to do, a priori, with the class named ex:Network, although it has the same name. This is called "punning" in the OWL 2 specification.

    There is a third way: change your knowledge model such that you do not encounter this problem. I do not know your ontology, but it could be hinting at an antipattern that you should avoid.