RE: TODO++: daml-ont TallThing

On November 1, McBride, Brian writes:
> > > There are a couple of minor nits in the example ontology:
> > > 
> > > 1) Father is desribed as having range Man, but presumably
> > >    inherits domain Animal from Parent.  Mother is similar.
> 
> A mother of a fox is not human.  I'd expect the domain and range
> to match i.e. domain of mother is person if range is woman, or
> range of mother is female animal if domain is animal.
> 
> A real nit - sorry.
> 
> Brian

This is another example of a point I made in an earlier discussion on
rdf-interest, namely that domain and range restrictions are very
strong assertions, and that a value restriction on the domain class is
usually more appropriate. 

For example, when the domain and range of a property P are restricted
to classes D and R respectively, the intended meaning often is (or
should be) that IF (i,j) is an instance of P AND i is an instance of D
THEN j must be an instance of R. This can be expressed in OIL (and
DAML-O) using a value restriction on the class D.

e.g., in OIL:

<rdfs:class rdf:ID="D">
  <oil:hasSlotConstraint>
    <oil:has-value>
      <oil:hasProperty rdf:resource="#P"/>
      <oil:hasClass rdf:resource="#R"/>
    <oil:has-value/>
  <oil:hasSlotConstraint/>
<rdfs:class/>


or in DAML-O

<Class ID="D">
  <restrictedBy>
    <Restriction>
      <onProperty resource="#P"/>
      <toClass resource="#R"/>
    </Restriction>
  </restrictedBy>
</Class>