- From: Jos De_Roo <jos.deroo@agfa.com>
- Date: Sat, 1 Mar 2003 11:16:02 +0100
- To: "Tim Berners-Lee <timbl" <timbl@w3.org>
- Cc: Bijan Parsia <bparsia@isis.unc.edu>, Brian McBride <bwm@hplb.hpl.hp.com>, Dan Brickley <danbri@w3.org>, Graham Klyne <GK@ninebynine.org>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, pat hayes <phayes@ai.uwf.edu>, RDF Core <w3c-rdfcore-wg@w3.org>, w3c-rdfcore-wg-request@w3.org
[...]
>>Use case: I want to add 'foaf:uncle' to my FOAF vocabulary at
>>http://xmlns.com/foaf/0.1/ and intend to express as much of the
conventional
>>meaning of 'uncle' as I can with the technology available, ie. RDFS +
>>OWL + N3 + HTML/prose. In the case of 'uncle', most of the meaning is
invisible
>>to RDF/S and OWL. But most of it could be handled by N3 rules, assuming
>>we had foaf:parent, foaf:sibling, gender vocab etc.
>>
>>
>Well, that is a big assumption. So let's be sepcific
>
>{ ?x :uncle ?y } log:iff { ?x :parent [ :brother ?y ] }.
>
>is a precise definition of the term for someone for whom parent and
brother
>are defined. But this of course doesn't really help us as somewhere the
>thing has to be grounded in english.
>
>'"?x :uncle ?y" indicates that y is the uncle of x'
>
>is an english definitoin which will do for a lot of people.
>I would expect a good spec to have both.
>The formal information is a useful axiom.
I don't think it's an iff as it could be the case
that
{?c :parent ?p. ?p :sister ?s. ?s :spouse ?u}
=>
{?c :uncle ?u}.
and the ?c, ?u substitutions for those cases aren't
necessarily implying
{?c :parent ?p. ?p :brother ?u}.
-- ,
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
PS1 That's not to say that iff's are meaningless ;-)
Received on Saturday, 1 March 2003 05:16:55 UTC