subproperty question from Ian Horrocks on 2001-01-25 (www-rdf-interest@w3.org from January 2001) (original) (raw)

On January 25, Arjohn Kampman writes:

Stefan,

In general one wouldn't expect a sub-property of a transitive property to be transitive itself, e.g., parent as a sub-property of ancestor.

Ian

Related to this: I think you can state that, for a property to be transitive, all of its superproperties have to be transitive too.

From the RDF/S spec: "If some property P2 is a subPropertyOf another more general property P1, and if a resource A has a P2 property with a value B, this implies that the resource A also has a P1 property with value B."

Now consider P2 to be a transitive property and you have the following situation:

X  --P2-->  Y  --P2-->  Z

In that case, X would also be related to Z through P2 and thus, as P1 is a superproperty of P2, also through P1. Therefore P1 also has to transitive.

Please correct me if I'm wrong,

You are wrong I'm afraid. Here is a counter example:

P1 = {(x,y),(y,z),(x,z),(w,x)} P2 = {(x,y),(y,z),(x,z)} P3 = {(x,y),(y,z)}

As you can see, P3 is a subPropertyOf P2 is a subPropertyOf P1. Only P2 is transitive.

Regards, Ian

Received on Thursday, 25 January 2001 12:27:19 UTC