W3C home > Mailing lists > Public > www-rdf-logic@w3.org > May 2001

RE: What do the ontologists want

From: dehora <bill@dehora.fsnet.co.uk>
Date: Sat, 19 May 2001 17:13:14 +0100
To: "pat hayes" <phayes@ai.uwf.edu>
Cc: <www-rdf-logic@w3.org>
Message-ID: <DCEBKOHMHCKKIAAPKLLMGELICHAA.bill@dehora.fsnet.co.uk>
 
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: >1: RDF reification is a technique that turns statements into URIs.
: >2: KR reification is a technique that turns predicates into terms.
: >
: >in RDF:
: >
: >3: a statement is not a predicate.
: >4: a statement is not a resource.
: 
: pat hayes:
: ? I thought a resource could be anything (?) 

I prefixed this with "in RDF", but I should know better than to use
the term "resource" so freely. Operationally in RDF, a resource is
something identified by a URI (that may have anchor ids) as per
rfc2396. With my implementers hat, a resource is synonymous with a
URI. In code I'm going to call my resource object a Resource, not,
SomethingIdentifiedByAURIWhichMayOptionallyHaveAnchorIDs. So when I
instruct a machine to hang a property value off a resource, I intend
that this instruction will describe the resource not the URI that
denotes it. Thus:

urn:elvis urn:says urn:thankyuhveriimuj

describes nothing about the URI urn:elvis, it's intended to describe
whatever urn:elvis denotes: in this case, my neighbours lawn mower.
This touches on the matter of social contract Dan Brickley mentioned.
We agree that URIs identify things and we agree to call these things
resources. If we didn't:

urn:elvis, urn:says, urn:thankyuhveriimuj

is not any more useful than saying either:

"elvis", "says", "thankyuhveriimuj"
http//www.w3.org/Home/Lassila, creator, "Ora Lassila"

as Drew McDermott pointed out, this last seems to say like the string
created the website (actually it doesn't look like it says anything
since the predicate isn't a URI). Without prior agreement that URIs
denote things then RDF is simply describing relationships between
URIs. With agreement that URIs denote things, RDF is describing
relationships between things.

I'll have another go:

4: in RDF an individual statement is not identified by a URI
optionally with an anchor id.
4.a: with RDF, one might say that "an individual statement is not a
resource, as it is not identified by a URI"
5: a predicate is identified by a URI optionally with an anchor id.
5.a: with RDF, one might say that "in RDF a predicate is a resource,
as it is identified by a URI"
6: a URI optionally with an anchor id clearly doesn't need to be
reified to make a statement about what it identifies.
6.a: a URI optionally with an anchor id needs to be reified to make a
statement about it.
6.b: with RDF, one might say that "RDF allows us to make statements
about resources through their URIs"
6.c: with RDF, one might say that "in RDF we use URIs to talk about
resources which they identify, not about URIs. URIs are not
resources." 
7: things that are not identified by a URI optionally with an anchor
id cannot have statements made about them (modulo issue on literals
being statement subjects).
7.a: with RDF, one might say that "in RDF we can only speak about
resources" 
7.b: with RDF, one might say that "in RDF an individual statement
cannot be spoken about".
8: an rdf_reified_statement is a statement identified by a URI
optionally with an anchor id.
8.a: with RDF, one might say that "in RDF a reified_statement serves
to make an individual statement a resource"
9: an rdf_reification consists of 4 statements, which share a
rdf_reified_statement.

: pat hayes:
:I am still trying to 
: find out what 'resource' means, but Dan Connolly tells me that:
: the standard [definition of resource] is RFC2396:

In RDF, a resource is something identified by a URI (that may have
anchor ids) as per rfc2396. That's all there is to it. I find it's
useful way to think when it comes to implementing code.  That may
seem a backways determination; if I create a URI do I create a
resource for it to identify? This is moot, the RDF machine can't
access a resource directly anyway, but it allows for the description
of say, unicorns. 


: pat hayes:
: I think that we have come to similar conclusions, if by rather 
: different routes.

I'd probably prefer yours if I could understand it :)

regards,
Bill

- ----
Bill de hOra : InterX : bdehora@interx.com 

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Received on Saturday, 19 May 2001 12:13:33 UTC

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