W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > October 2001

Re: big issue (2001-09-28#13)

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Fri, 5 Oct 2001 13:31:57 -0500
Message-Id: <p05101016b7e3ac0b0c5f@[205.160.76.189]>
To: Sergey Melnik <melnik@db.stanford.edu>
Cc: w3c-rdfcore-wg@w3.org
>Pat Hayes wrote:
>>
>>  >On Friday, September 28, 2001, at 12:31  PM, Sergey Melnik wrote:
>>  >
>>  >>   Tracked as: #rdfms-literals-as-resources
>>  >>   Dependent issue: #rdfms-literalsubjects, would be resolved immediately
>>  >>if literals are resources
>>  >
>>  >Oh? I don't agree with that. We can say that literals are resources
>>  >(indeed, I think it's pretty clear we have to) but we don't have to
>>  >give them URIs, or a place in the RDF abstract syntax.
>
>Granted, but see below.
>
>>  I agree. In the same vein:
>>
>>  >
>>  >These are the (possible) consequences:
>>  >
>>  >c1) Resources and literals are disjoint
>>
>>  I don't think this is a consequence. Literals are not URIs, but they
>>  can be resources, and literal values can definitely be resources.
>
>Speaking of resources and literals, I meant "resource constants" and
>"literal constants" (still have to adapt to the new terminology...) It
>seems that the term for resource constants that is consistent with the
>MT draft is "URI" or "referring expression".
>
>In MT, URIs denote resources, and (apparently) literals denote literal
>values. Terminologically, this does not seem very elegant. Pat, is there
>a way to name the things more uniformly, e.g. resource -> resource value
>(after all, resource constants may end up having two parts, namespace +
>local name), or string -> literal, etc.?

Well, much of this terminology was set before I got involved, and I'm 
just trying to accomodate to it. (I just discovered I got 'URI' 
wrong, so the next draft is going to be even less elegant.) I guess I 
have never understood 'resource' to be restricted to syntax, though, 
and can't find any justification for that kind of usage.

I've never been quite sure exactly what a literal really is (eg if we 
say that 50 is a literal , do we mean the numeral or the number?) but 
I assumed in the MT that it was on the syntax side, and invented the 
'literal value' phrase just to keep the terminology straight.

Heres the terminology I propose to use in the next MT draft:

Node labels are called 'URI references' (refer RFC 2396), or URIrefs 
for short, and 'literals'. I will make a short speech about the MT 
not being committed to any particular story about exactly how 
literals are syntactically encoded, but we will use N-triples for the 
present. If I want to say something about both of these at once, I'll 
just call them 'labels'.

The term 'resources' is used as a kind of blanket term for the things 
in the universe of discourse, whatever they are, rather in the way 
that logicians use words like 'entity' or 'individual' (these are the 
subjects of the triples and anything that could be the denotation of 
a blank node.) Literal values are whatever literals denote; nothing 
is assumed one way or the other about whether or not literal values 
(or indeed literals for that matter) are resources. If you have an 
alternative suggestion for what to call literal values, I have no 
particular attachment to that phrase; it was supposed to just be a 
neutral abbreviation of 'semantic value of a literal'.

Pat
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Received on Friday, 5 October 2001 14:31:59 EDT

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