RE: Properties of Properties Question

Using hypothetical 'RestrictionOfProperty' and 'toProperty' constructs, a
concrete example would be:

<daml:ObjectProperty rdf:ID='SuspectedAssociation'>
     <daml:subPropertyOf>
         <daml:RestrictionOfProperty>
             <daml:onProperty rdf:resource='#EvidenceOf'/>
             <daml:toProperty rdf:resource='#ObservatedAssociation'/>
         </daml:RestrictionOfProperty>
     </daml:subPropertyOf>
 </daml:ObjectProperty>

Allowing you to build evidence of suspected associations (e.g.
conspiringWith, friendOf) based on observable associations (e.g. worksWith,
meetsWith) but disallowing suspected associations as direct evidence. This
example could also be stated differently, restricting the evidence to be a
Class 'Observation':

<daml:ObjectProperty rdf:ID='SuspectedAssociation'>
     <daml:subPropertyOf>
         <daml:RestrictionOfProperty>
             <daml:onProperty rdf:resource='#EvidenceOf'/>
             <daml:toClass rdf:resource='#Observation'/>
         </daml:RestrictionOfProperty>
     </daml:subPropertyOf>
</daml:ObjectProperty>

The crux of the problem is the lack of a 'RestrictionOfProperty' analogous
to daml:Restriction. It only seems reasonable to me that properties of
properties should be able to have restrictions in the same way properties of
classes can. Is there a reason that this should not be the case, other than
an implementation limitation of DAML+OIL?

- Lewis
__________________________________________
Lewis L Hart 
GRC International           lhart@grci.com
1900 Gallows Rd.       Voice (703)506-5938
Vienna, Va 22182         Fax (703)556-4261



-----Original Message-----
From: Peter F. Patel-Schneider [mailto:pfps@research.bell-labs.com]
Sent: Monday, October 22, 2001 4:32 PM
To: lhart@grci.com
Cc: www-rdf-logic@w3.org
Subject: Re: Properties of Properties Question


From: "Hart, Lewis" <lhart@grci.com>
Subject: Property's of Properties Question
Date: Mon, 22 Oct 2001 16:07:47 -0400

> A simple question, with hopefully a simple answer. Is it possible to place
a
> restriction on the property of a property in DAML[+OIL]? 

No.  At least I don't think so.  Certainly not in general.  

> What I would like to say, for example is:
>  
> <daml:ObjectProperty rdf:ID='Foo'>
>     <daml:subPropertyOf>
>         <daml:Restriction>
>             <daml:onProperty rdf:resource='#Bar'/>
>             <daml:toProperty rdf:resource='#Baz'/>
>         </daml:Restriction>
>     </daml:subPropertyOf>
> </daml:ObjectProperty rdf:ID='Foo'>
>  
> Except for the fact that daml:Restriction is a daml:Class and
> daml:toProperty doesn't exist, this would be fine. 

If you have to use except, it isn't DAML+OIL.  :-)
daml:Restriction forms a daml:Class, which is not really suitable as the
superproperty of a property.

All that said, RDF allows entities to be both classes and properties, so
what you are doing above is to
1/ create an unnamed class with a malformed restriction, which means that
   there will be no semantic constraints for the class
2/ assert that Foo is a subproperty of the property that has the same
   identity as the class

So you have said roughly the same thing as 

 <daml:ObjectProperty rdf:ID='Foo'>
     <daml:subPropertyOf>
         <rdf:Property />
     </daml:subPropertyOf>
 </daml:ObjectProperty rdf:ID='Foo'>

as far as DAML+OIL is concerned.

> Thanks - Lewis

I don't think that you can do what you want.  However, if you give a
concrete example, I would be able to tell for sure.

Peter F. Patel-Schneider
Class of '72, GRCI

Received on Tuesday, 23 October 2001 09:26:00 UTC