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Re: Some TAG review of "Cool URIs for the Semantic Web"

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 20 Sep 2007 15:59:23 -0500
Message-Id: <p0623091bc31884d69db8@[]>
To: Dan Connolly <connolly@w3.org>
Cc: Tim Berners-Lee <timbl@w3.org>, Technical Architecture Group WG <www-tag@w3.org>, Susie Stephens <susie.stephens@gmail.com>

>My main point is about numbers and numerals, near
>the end; I hope you'll read that far before you argue any of the
>lesser points...
>Pat Hayes wrote:
>>>Pat Hayes wrote:
>>>>>7. "On the Semantic Web, URIs identify not just Web documents, 
>>>>>but also real-world objects like people and cars, and even 
>>>>>abstract ideas and non-existing things like a mythical unicorn. 
>>>>>We call all these things resources."
>>>>>Of course many people would consider the Traditional Web to 
>>>>>include mailto: links. Suggest:
>>>>>"On the Semantic Web, http: URIs identify not just Web 
>>>>>documents, but also real-world objects like people and cars, and 
>>>>>even abstract ideas and non-existing things like a mythical 
>>>>>unicorn. We call all these things resources."
>>>>This seems to me to embody the central error which is causing so 
>>>>much trouble. In what sense can a URI (or indeed any name: the 
>>>>fact that is a URI is irrelevant in this case) be said to 
>>>>"identify" a real-world or nonexistent entity? The direct answer 
>>>>is, it CANT. To even use this word "identify" in this sense and 
>>>>in this kind of a case, is clearly and provably WRONG.
>>>It seems pretty clear that the name "Dan Connolly" identifies
>>>me and that I am a real-world entity.
>>You are real, I grant you. And "Dan Connolly" is your name. But 
>>does that name "identify" you?  Seems to me that in order to 
>>justify this
>>usage, it would have to be that if someone who didn't know you or 
>>anything about you were given just that name, "Dan Connolly", a 
>>string of 12 characters, that they could figure out from that 
>>string which real-world entity you actually are. Maybe not *locate* 
>>you, but at least single you out from all the the other DCs there 
>>might be. But in fact they couldn't, because there are others with 
>>the same name, who therefore it also 'identifies' if it identifies 
>>you. (Eg 
>>Is that enough of a proof?
>It helps me understand what you mean, yes.
>Your point here is about scope. URIs are intended to
>have universal/global scope, so it's less clear that this form
>of argument applies

I agree that is one response. (I was replying to your challenge as 
worded.) Taken seriously however this presumes that URIs will somehow 
become an unambiguous global naming system, which I find unlikely, 
precisely because *when used as names* they will have all the 
ambiguity issues that all other names have. The fact that they are 
URIs isn't going to help any with making them behave any differently 
*as names*. And in fact, this has already happened, almost 
immediately when the first RDF/OWL ontologies were published. What 
does http://www.w3.org/2002/07/owl#Class identify?

>, though perhaps it still does... in any case...
>>Maybe this criterion is set too high, although I kind of 
>>transcribed it from the Web requirements for the "identifies" 
>>relationship between URIs and 'information resources'. But if this 
>>is too high, why do you and the TAG insist on saying "<name> 
>>identifies <thing>" instead of the more usual and completely 
>>non-puzzling "<name> is a name of <thing>" or even "<name> refers 
>>to <thing>" ?
>I have a hard time imagining that changing "identifies" to "refers"
>or even "is a name of" would make much difference to the audience
>of this document.
>'name' and 'identify' are synonyms, according to thesaurus.com.

True, but thesauri are very crude tools for pining down meanings. And 
the two lists of synonyms are strikingly different.

>That source doesn't give 'refer' and 'identify' as direct synonyms,
>but it says 'indicate' is a synonym of 'refer' and 'identify' is
>a synonym of 'indicate'.
>Given that it's pretty much a coin flip at this level, I think
>it's reasonable to use "identify" in order to help introduce
>the reader to the standard "Uniform Resource Identifier"

What worries me is that 'identifies' DOES have these other 
connotations when it talks about the URI/information-resource 
relationship. There, indeed, the identifier IS enough to get you to 
the resource; the mapping IS globally unique, IS unambiguous, etc.. 
Its a very easy sideways slide to presume that all this will be true, 
or close to true, for the URI/non-information-resource mapping. But 
it ain't.

>>Isn't this 'identifies' usage supposed to suggest SOME kind of 
>>similarity between the URI-to-information-resource relationship and 
>>the URI-to-Dan Connolly relationship?
>Yes, of course.

Well, you can say that the first one is a (very) special case of the 
second, with the Web added, I guess. But even that isn't obvious: its 
only true by stipulation.

>>We usually say "identifies" rather than merely "is a name of" when 
>>the identifier can be USED to single out the thing named from the 
>>universal multitude,
>  > just as an xxtp: URI can be USED to actually GET something.
>That's not at all clear to me. What well-known
>works make that distinction?

Any use of "identifier" in programming language metatheory. 
"Identification parade". "Do you have any identification?" (Not 
usually enough to just give your name.) "She identified him as the 
man who stole her poodle." And see the definitions below, all of 
which provide a sense that to identify something is to recognize it, 
classify it, establish its (unique?) identity, etc.. , and that 
therefore an 'identification' is something that goes beyond merely 
labelling something with a name.

>A few seconds of searching yields evidence to the contrary,
>i.e. that "name" and "identify" are synonyms:

No, that "identify" is one case of "name". Which is true enough for 
government work, I will agree. But not all names are identifiers, is 
my point.

>"Identifiers (IDs) are lexical tokens that name entities."
>  -- http://en.wikipedia.org/wiki/Identifier

Princeton Wordnet (first definition): recognize as being; establish 
the identity of someone or something.

Teaching Today: Establish the essential characteristics of.

Adprima: To indicate the selection of an object of a class in 
response to its class name, by pointing, picking up, underlining, 
marking, or other responses.

Farlex Free Dictionary:
1.  To establish the identity of.
2. To ascertain the origin, nature, or definitive characteristics of.
3. Biology To determine the taxonomic classification of (an organism).

Pimsleur Vocabulary: to recognize someone or something and to say who 
or what they are.

>>But names can't be used like this, in general: they are just names. 
>>They aren't anything like addresses or identifiers, because they 
>>don't identify. They just name.
>That's argument by assertion; I don't find it persuasive at all.

Well, surely it is not very controversial to say that names name. And 
Ive already argued (and obviously it generalizes) that names like 
"Dan Connolly" and "Patrick J. Hayes" don't identify. In fact there 
are at least two Patrick J. Hayes's living in Pensacola.

>(I could give a counter-argument, but I'm sure you a have
>seen it before and it didn't convince you then, so it's
>probably not worth going into again now.
>In case anybody is new to this conversation,
>see http://www.w3.org/DesignIssues/NameMyth for the position
>that I hold.)
Insofar as I follow that document, it seems to be  about names in 
computational systems, and largely concerned to distinguish 
identifiers from mere addresses. And I'll go along with all that, for 
the reasons given there. But this seems to be a rather different 

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Received on Thursday, 20 September 2007 20:59:38 UTC

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