W3C home > Mailing lists > Public > www-rdf-interest@w3.org > February 2001

Mapping External Triples Structures Into Your Own Systems

From: Sean B. Palmer <sean@mysterylights.com>
Date: Fri, 23 Feb 2001 17:13:17 -0000
Message-ID: <005201c09dbc$1b281cc0$d9d993c3@z5n9x1>
To: <www-rdf-interest@w3.org>
Stop me where I'm wrong...

Let's say we have the following snippet of easily understandable N3:-

     @prefix : <http://infomesh.net/2001/02/ns1/> .
     @prefix myns: <http://webns.net/2001/02/ns2/> .
     :x :property1 :y .
     :x :property1 myns:z .

Now... :x is linked somehow to :y with :property1. No need to think of
examples, that's all we need to know. Let's also say that it is
*essential* for the machine that uses this schema to know that :x can
take on the property1 of *both* :y and myns:z. Otherwise it won't
Now, what if I take out the second line, and move it elsewhere, but
replace it with another bit of information.

     @prefix : <http://infomesh.net/2001/02/ns1/ > .
     @prefix myns: <http://webns.net/2001/02/ns2/> .
     :x :property1 :y .
     :x :property1 :q .
     :q = myns:p .

My system is now completely broken. It needs to know, for some reason,
that ":x :property1 :y, myns:z .", and this cannot be worked out from
the information above.

However, what if the Schema at http://webns.net/2001/02/ns2/ contained
the following:-

     @prefix : <http://webns.net/2001/02/ns2/> .
     :p = :z .

In other words, it needs to know that ":x :p1 myns:z". At the moment
it knows that ":x :p1 :q", and also that ":q = myns:p". If my system
could just work out that "myns:p = myns:z", then the thing would work.

How can it get this knowledge... well (take a deep breath), if my
program dereferenced the URI for the second schema (shock horror), it
finds that it understands what the URI *means* in this context (it
explicitly trusts that server, because I programmed it to). It did
need to understand the HTTP, and the N3 needed to derive that fact,
but at least it now correctly finds out that ":x :property1 :y, myns:z
.", and the dang thing works at last. All because it dereferenced a

Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
[ :name "Sean B. Palmer" ] :hasHomepage <http://infomesh.net/sbp/> .
Received on Friday, 23 February 2001 12:12:41 UTC

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