# Re: Challenge for RDF Gurus :)

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Mon, 18 Feb 2002 18:31:59 -0600
Message-Id: <p0510140ab897498542e5@[65.212.118.219]>

```>   Just for playing.
>
>   if you followed the mails between Brian McBride and I, you will know
>about the different semantics for range and domain properties.
>
>   His proposal is the official, mine is just what I think it should be
>(just me)
>
>   So, I wanted to propose to the 'gurus' a little challenge
>
>   Try to represent that in rdf schema
>
>   Class A
>   Class B
>
>   property c(range(A or B), domain(A and B))

I take it that this means that the range is the union and the domain
is the intersection. The official answer is that you can't. What you
can do is this:

_:x rdfs:range A .
_:x rdfs:subPropertyOf C .
_:y rdfs:range B .
_:y rdfs:subPropertyOf C .
C rdfs:domain A .
C rdfs:domain B .

This says that the domain is contained in A intersect B, and that the
range is contained in a class containing both A and B. That's the
best you can do in RDF since it doesn't have any kind of negation or
'lower-bound' construct that could prevent a range or domain being
smaller than stated.  If you want to be more exact about upper and
lower bounds of classes, you will need to use a more expressive
language, such as DAML.

Pat Hayes

PS. BTW, if you think of 'domain' and 'range' in terms of category
theory, then you would expect multiple ranges to intersect and
multiple domains to union. So learn to think about domains and ranges
differently. RDF properties are not really like functors or mappings;
they are really binary relations. The distinction between domain and
range is just the distinction between first and second argument
position, not a deep matter. So one would expect them to at least go
the same way under multiple assertions, and intersecting them is the
natural way to go since RDF triples are basically conjoined rather
than disjoined in an RDF graph.

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Received on Monday, 18 February 2002 19:31:50 UTC

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