Re: Dealing with qualified expressions in DAML

> Date: Thu, 26 Sep 2002 15:53:24 -0400 (EDT)
> Subject: Re: Dealing with qualified expressions in DAML
> From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
> 
> > I'm afraid that I have one more question that I would like to pose regarding 
> > this discussion.  Does this "shared extension" side effect take place when 
other 
> > restriction elements are used instead of just "hasClassQ"
> > 
> > For example 
> > 
> > <daml:Class rdf:ID="Rabbit">
> >   <rdfs:subClassOf>
> >     <daml:Restriction>
> >       <daml:onProperty rdf:resource="#Eats"/>
> >       <daml:toClass rdf:resource="#Vegitables"/>
> >       <daml:hasValue rdf:resource="#Carrots"/>
> >     </daml:Restriction>
> >   </rdfs:subClassOf>
> > </daml:Class>
> > 
> > Now before you said:
> > >     It is a logical consequence of the information specified that each of
> > >     the restrictions thus formed has the same extension.
> > So does that mean that 
> >    {things that eat Vegitables}
> >    has exactly the same elements as 
> >    {things that eat Carrots}
> 
> Yes, except that that is not what the syntax above says.  To get this you
> need two toClass pieces.n

So then does the above syntax just define the class
	{things that only eat vegitables} intersect
	{things that eat a carrot}
without specifying this "is the same class as" side effect?

Just to be sure I understand your meaning, the "sub-restrictions" having the 
same extention occurs whenever a particular tag in the <Restriction> occurs more 
than once.  Is that right?

Thanks,
John

Received on Thursday, 26 September 2002 16:55:20 UTC