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

Re: universal languages

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 5 Feb 2001 22:14:47 -0600
Message-Id: <v0421011eb6a52580544c@[]>
To: "Sean B. Palmer" <sean@mysterylights.com>
Cc: <www-rdf-logic@w3.org>
> > What I don't see the reasoning behind is the insistence that
> > URI's should be used to name *everything*.
>So what's the alternative: string literals?

The alternative is, in general, unicode character strings, or 
numerals, or whatever else I and the people I am communicating with 
might want to use to refer to anything. Hell, it might be little 
movie gifs one day for all I know. Why should this be restricted to 
some predetermined syntax?

> But there is no control over
>string literals, there is no agremment on what "my uncles left thumb" is.

Of course not. There is no agreement about what anything accessible 
through a URI means, either. Any such agreement must, in the end, be 
a social agreement within a community to use a name in a certain way 
- it cannot be 'controlled' -  but what we can do is post our 
assumptions in a publicly readable form in a publicly accessible 
place (which is indeed where URI's are a natural tool to use.)

>But if you give that a URI, you are asserting a particular context for
>which that can be used. In other words, if I use that URI, you can define
>it as meaning your uncles left thumb

No no, you can't have it both ways. HOW do I define it to mean my 
uncle's left thumb? By putting something at the location indicated by 
the URI which identifies my uncle's left thumb? But why don't I use 
that (whatever it is) directly and save you the trouble of fetching a 
URI? You arent going to have learned anything new about what 
something means just by forcing it to be sent to you by optical 
fiber, and neither is your software. If I want to use a URI to 
specify a particular context (whatever that means), then fine. But I 
see no reason why anyone should be *forced* to do this.

>, but only in the context of whatever
>tools you are using that namespace with. I think there is some confusion
>between machine processability and natural language here: there are
>*limits* to what machine processing can do.

Believe me, I am vividly aware of what those limits are. I've been 
working in AI for 25 years. But machines can draw conclusions from 
axioms which do not use URI's, for sure.

>The whole point for using URIs
>is that they are decentralized; anyone can set one up. While it is true
>that you can't use URIs to represent everything, you can use them to name
>anything which is namable.

Well, that is either trivial or false. You can, of course, put a name 
at a location with a URI and then use that. So in that sense URI's 
are universal, but that's a trivial sense, In that sense every piece 
of paper is in an envelope because you could put it in one.  But it 
is not true that every possible *name* is a URI. My name is not a 
URI. "Boston" is not a URI, and neither is "4,367".

Pat Hayes

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Received on Monday, 5 February 2001 23:11:54 UTC

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