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Re: DAML: restricting number of elements in a list

From: Steven Gollery <sgollery@cadrc.calpoly.edu>
Date: Thu, 07 Feb 2002 13:30:52 -0800
Message-ID: <3C62F20C.FDBB5FC9@cadrc.calpoly.edu>
To: www-rdf-logic@w3.org
Ken,

Thank you -- that seems reasonable. Just to make sure that I'm understanding,
here's some DAML that I think implements what you're describing:

<daml:Class rdf:ID="Point">
</daml:Class>

<daml:Class rdf:ID="VertexList">
  <rdfs:subClassOf rdf:resource="daml:list"/>
  <rdfs:subClassOf>
    <daml:Restriction>
      <daml:onProperty rdf:resource="daml:item"/>
      <daml:toClass rdf:resource="#Point"/>
      <daml:minCardinality>3</daml:minCardinality>
    </daml:Restriction>
  </rdfs:subClassOf>
 </daml:Class>

I think that restricts the class of the items to Point and the number of items
to 3 or more.  Is that right?

Thanks again,

Steve


Ken Baclawski wrote:

> The daml:item property relates a list to each of its elements.  One can
> impose a daml:minCardinality restriction on the daml:item property to
> ensure that the number of vertices in a polygon is at least 3.
>
> Ken Baclawski
> Ken@Baclawski.com
> UBOT Project
>
> On Wed, 6 Feb 2002, Steven Gollery wrote:
>
> > I'm working on an ontology in DAML that includes some geometric
> > concepts. I would like to be able to somehow define a property Vertices
> > whose domain is the Polygon class and whose range is ordered collections
> > of instances of the Point class, where the length of the ordered
> > collection is at least three.
> >
> > It would be fairly straightforward to say that each Polygon must have at
> > least three values of a Vertex property which is restricted to class
> > Point, but that would lose the idea the vertices have an order -- the
> > order is obviously a fundamental part of the semantics for the polygon.
> >
> > Does DAML provide any way to restrict the number of elements in a list?
> > Or is there some other way to do what I need here?
> >
> > Thanks in advance,
> >
> > Steve Gollery
> > sgollery@cadrc.calpoly.edu
> >
> >
Received on Thursday, 7 February 2002 16:29:22 GMT

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