Re: URIs as names (was: What do the ontologists want)

># Chimpanzees and gorillas can use names like this; so
># what is all the fuss about? Which makes me think that this can't
># really be what is meant by a URI. But I still don't know what else
># there is to the notion.
>
>reductio ad absurdum doesn't really help here.

I wasnt intending reductio. Trained chimpanzees really do use names 
to refer to things. My point was that it is a very basic language 
function, probably the most basic of all.

>Personally,
>I think the fuss is just because people haven't figured out
>how the mystical power of the URL turned improverished hypertext
>into the multi-billion-dollar World Wide Web.

:-)

>The use of URIs in RDF and as XML namespace names to identify
>things other than network resources is a bit of semantic extension
>that doesn't work all that well. You can certainly imagine
>defining a URI scheme that would work to name a grain of
>sand on a Pensacola beach, but is it really a good idea to
>do so? It's kind of like using Goedel numbers instead of
>equations.

My point is really that logic assumes, typically, that there is an 
infinite stock of 'new names' available, so that we can say things 
like: thingy exists; call it 'foo-5767', and then go on talking about 
foo-5767 as though it were our best friend. One has a basic 
assumption of lexical freedom; the use of names is just a way of 
referring to existents, and really all they have to do in order to 
qualify to be nameable is to exist (and in some logics not even 
that). So if there is some particular grain of sand I want to talk 
about (My dear, do you know, yesterday I picked up some sand on the 
beach, and one of the grains was green!) then we can give it a name 
and talk about it. But having to create an entire URI schem to do 
that seems like overkill.

>The simplest way I have of coping with all of this is to note
>that URIs (as defined by RFC 2396, at least) are just syntax,
>a protocol element that derives having semantics almost entirely
>from the context in which it is used. (Early drafts of RFC 2396
>were titled 'syntax and semantics', and 'semantics' was dropped).
>A URI used in a HREF of an A element in a HTML web page has one
>meaning, based on the expected behavior when the link is clicked;
>the same URI used as a namespace name in an xmlns attribute has a
>different meaning, because it is not expected to be "clicked".
>RDF supplies yet another context, but currently isn't clear about
>what it intends the meaning of the URIs within it to be.

Ah, that makes a lot of sense.

>Part of the problem is that there's a lot of sloppiness about the
>level of quoting or indirection. Some RDF statements seem to be
>about the actual resources that a Uniform Resource Identifier
>identifies, and others are about resources that are merely
>described or correlated with those other resources.

Right. And some are about resources that consist of further things 
with URIs in them.

>Getting
>the level of indirection right is hard; we haven't been explicit
>about when EVAL is called.

Precisely, I agree entirely.

Pat

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Received on Saturday, 19 May 2001 22:54:14 UTC