on Fri. Dec. 28, 2007 at 9:50 PM, Pat Hayes wrote: (01)
> >on Fri. Dec. 28, 2007 at 5:31 PM, Pat Hayes wrote:
>>>
>>>>on Wed. Dec. 26, 2007 at 7:30 PM, Pat Hayes wrote:
>>>>[snip]
>>>>
>>>>JB>>Reminds me of a question I keep having with regard to URIs in the
>>>>>>Web Architecture. There doesn't seem to be any attempt to distinguish
>>>>>>between each occurrence (I sometimes call it an utterance) of a URI
>>>>>>and its establishment.
>>>>>
>>>>PH> Indeed, there is not. On the contrary, there is an insistence that
>>>>no
>>>>>such distinction be made. To make it is an architectural error. That is
>>>>>the whole point of URIs, if you think about what they are mostly used
>>>>>for. If your browser, in its context, were to interpret a URI
>>>>>differently from the website it identifies, in its context, then the
>>>>>entire Web would stop working.
>>>>>
>>>>>> And in fact, it seems to be argued often that this is by design and
>>>>>> intentional, yet nowhere is are there methods for dealing with what
>>>>>> seems to be inevitable contextual differences between each occurrence
>>>>>> of a URI.
>>>>>
>>>>>That is exactly the point. There should not be any such contextual
>>>>>differences. The CL logic is designed to eliminate them. If they, as
>>>>>you say, 'inevitable', then the Web must be broken. But on the whole it
>>>>>seems to work reasonably well.
>>>>>
>>>>>>In other words, it sounds like IKL aims for the same goal
>>>>>
>>>>>IKL and CL are similar in this aspect, of having globally transparent
>>>>>meanings for names.
>>>>>
>>>>>> but includes some machinery for achieving it, while the Web
>>>>>> Architecture claims that it is so by engineering design.
>>>>>
>>>>>Well, URIs on the Web have a dual aspect: they provide access to
>>>>>"information resources" (for the meaning of this jargon, go to the W3C)
>>>>>and they also are used in RDF and OWL to *denote* arbitrary things. The
>>>>>relationships between these two roles are subtle and controversial, and
>>>>>not always described very clearly. But certainly, both the Web
>>>>>architecture and the CL logic assume that names denote uniformly, not
>>>>>differently in different 'local contexts'.
>>>>
>>>>I just came across this in Tarski's 1944 paper, The Semantic Conception
>>>>of Truth: "...the fundamental conventions regarding the use of any
>>>>language require that in any utterance we make about an object it is the
>>>>name of the object which must be employed, and not the object itself. In
>>>>consequence, if we wish to say something about a sentence, for example,
>>>>that it is true, we must use the name of this sentence, and not the
>>>>sentence itself."
>>>
>>>Quite. The same basic point was made much earlier, and more humorously,
>>>by Johnathan Swift, in his description of the isle of Laputa.
>>>
>>>But this is not *strictly* true in human discourse. If there is some way
>>>to indicate the actual object without naming it, for example by pointing
>>>to it or brandishing it or looking pointedly at it, I can refer to a
>>>thing without naming it. We do this all the time. For example, I might
>>>pick up a vegetable in a supermarket and say to you, "Rutabaga?", using
>>>the vegetable itself as the object of my query. However, this can only be
>>>done in a setting where both you and I and the thing itself are equally
>>>part of the immediate common ground.
>>
>>I believe this is true of web objects. If I mention a URL to you then both
>>of us can use HTTP to access the same object at nearly the same time.
>>
>>>> This reminds me of my objection (due partly to my understanding of
>>>> your own arguments about it) to the current attempts to describe the
>>>> relationship between those two roles. For I think the same could be
>>>> said about the object that is accessed by using a URI utterance in an
>>>> HTTP system. To say of a web document that it is an information
>>>> resource, for example, it is the name of the object (the URI) which
>>>> must be employed, and not the object itself. What the current version
>>>> of the web architecture seems to be saying is that web objects, as
>>>> opposed to everything else, say what they are themselves.
>>>
>>>It would be more accurate to say that they respond in a characteristic
>>>way to a certain kind of action. If you stroke something and it purrs,
>>>you conclude it was a cat: but that doesn't mean that the cat itself is
>>>referring to anything. And even if it did, the purr itself can be viewed
>>>just as much a name as "cat" is. Similarly, the http response code is a
>>>symbolic signal emitted by the resource itself. In fact, given that the
>>>TAG ruling is that in this case, the URI refers to the resource, the
>>>situation is very similar to my calling your name while addressing a
>>>crowd, and you responding "yes, I'm here". Notice that this has you
>>>referring to you by using "I".
>>
>>Perhaps this is so, but how will this make it into RDF or OWL?
>
> It already is in RDF and OWL. That is, these languages presume that URIs
> denote things. There is currently some ambiguity about what exactly a
> plain URI (without a # extension) should denote: the current
> recommendation is that when that URI returns a 200 response to an HTTP
> GET, then it denotes the web resource at that http endpoint.
>
>>Doesn't this require that axioms be added to the specification?
>
> No. Axioms wouldn't be enough to stipulate this.
>
>>Doesn't this make it a special case?
>
> Well, yes, but its a very very common special case.
>
>>With that ruling, a large set of URI must be understood to be members of
>>the class "Information Resource"
>
> Not the URI, but what the URI denotes. Yes, almost all of them, in fact.
> But almost all extant URIs ARE being used to identify websites and web
> pages, so this has the merit of not requiring the entire Web to be
> re-engineered to suit RDF.
>
>>and furthermore, that class must be understood to be disjoint with all
>>sorts of other classes.
>>
>>>>In other words, to make utterances about a web object, you use the web
>>>>object itself (including the 200 OK), and not its name.
>>>
>>>No, you *use* the URI that accessed that web object, to also talk about
>>>it (eg in RDF or OWL)
>>>
>>>> This would be like insisting that, when talking about a car, you had
>>>> to insert the car itself in your speech somehow, as the subject of all
>>>> propositions about it. This, of course, would seem to have the great
>>>> advantage that everyone would always be referring to the same car -
>>>> unambiguously - regardless of any local context. But actually, I think
>>>> this is an illusion. Objects can't insert themselves into ontological
>>>> categories. Agents use names to put categories around objects like cars
>>>> or web documents for particular purposes. The universe just exists,
>>>> agents say what objects are by using language.
>>>
>>>Quite. But this is irrelevant to the point we were discussing.
>>>
>>>>So I don't agree it would break the web for each utterance of the name
>>>>(URI occurrence) of some web object to be used for any useful purpose,
>>>
>>>BUt wait, you have begged the question already. To say that a name is the
>>>name OF a given thing is to presume that all occurrences of that name are
>>>names of that one thing. WHich is exactly the point at issue. If names
>>>can change their referents on every occurrence, then the very notion of a
>>>"name of a thing" ceases to be meaningful.
>>
>>I see what you mean about saying "...name of some web object...", but it
>>looks like I begged the question by assuming what I am disputing! more
>>like self-destructing than begging.... On the other hand, I thought by
>>hedging with "useful" I avoided such cases of extreme variability as would
>>render it meaningless - oh well.
>
> The problem is that machines have no grasp of nuances like "useful", and
> this discussion is about conventions for machines to use, not people.
>
>>
>>But seriously, I feel like I must be missing something again about names
>>and contexts. Here is the problem. My name is "John", a good proper name,
>>which in the presence of my immediate family, nails me precisely, and very
>>efficiently. In another family, occurrences of the same name, "John",
>>refer equally well to other referents, with equal precision and
>>efficiency. This use of the term "context" appears to me very trivial and
>>ubiquitous.
>
> Ubiquitous, but not at all trivial.
>
>> Isn't this type of context the same as a "namespace" that occurs
>> frequently in programming languages?
>
> Not really.
>
>>It permits names to change their referents, if not on *every* occurrence,
>>at least on every change of context (or namespace). Or am I missing
>>something?
>
> The key point is, what would count as a 'context' for a context-dependent
> URI? Consider this scenario. You, sitting at your computer, use a URi to
> browse an interesting website, and you send me an email telling me about
> it and citing the URI. I then, sitting at my computer, two days later on
> the other side of the planet, type that URI into my browser. We expect
> that we will see the same website: but what do our two contexts have in
> common? It might be almost nothing: the times, places, browsers,
> countries, users, OSs, maybe even cultural and linguistic settings, can be
> completely different. It is inherent to the Web that the contexts of
> publication and of use of a URI can be arbitrarily different and far apart
> on every dimension, yet the URI is supposed to retain its meaning. (02)
Unless my relative ignorance is blinding me to something obvious, we seem to
be thinking of two different things. I am not thinking of the *uniqueness*
part changing with the context, so that a URI-access produces two different
sites, I'm thinking of the ontological classification of what is there. To
explain what I mean, here is an example: that of a fingerprint. Fingerprints
have for some time been used to identify suspects in criminal
investigations. A human fingerprint is considered unique, except in the case
of identical twins. It would seem to be an adequate identifier or *name* for
a person. But it might also be used for many other references. A gruesome
example, after an airliner crash, a fingerprint could be used to identify a
finger, or a hand, or an arm. On the other end of the scale, that same
fingerprint could be used to identify my nuclear family, since no other
family can possibly have a member with the same fingerprint. For the same
reason, it could be used to identify a football team, a nation, or a
species. It is a unique, distinguishing characteristic all right - of many,
many things. By itself, it is not clear which of these things a fingerprint
names. Each occurrence of the same identical fingerprint, which belongs to
one and only one person, might then have a different referent. The person
doesn't change - but what his fingerprint denotes in the context of its
occurrence does. So it is with a name (in context) or a URI: The
time-varying set of representations of the resource doesn't change, but
*what it is* may vary. (03)
Take the Moby Dick web-site URI example. In one context, say a group of
network admins, an occurrence of that URI may denote the bit stream encoding
itself, perhaps a certain section of the bit stream has the same signature
as a well known virus. In another context, that of the web-site admin,
another occurrence of the URI may denote that particular on-line version of
the novel Moby Dick, for it may contain punctuation errors that need to be
corrected. In yet another context, that of a literature professor, an
occurrence of the URI denotes the entire phenomenon of Moby Dick, the great
American classic, translated in many languages, subject of many articles.
This is how each occurrence of a URI could have a different referent, even
though each user GETs 'representations' of one single 'resource'. (04)
John Black
www.kashori.com (05)
>>>>even if different from other uses, all while HTTP returns the same
>>>>object for the same URI.
>>>
>>>Here you touch on a delicate point. IMO, there is indeed an important
>>>conceptual distinction to be made between the relationships of naming or
>>>reference, on the one hand, and 'accessing' or 'identifying' on the
>>>other, and many of the W3C discussions fail to make this distinction and
>>>so are hopelessly muddled. The http-range-14 decision can be summarized
>>>as: when a Web object returns a 200 response code, the URI which accessed
>>>it (ie the GETing of which resulted in the code being returned) must also
>>>be understood as denoting it. This is highly intuitive, so much so that
>>>many folk take it as so obvious as to not need saying, but it does need
>>>to be said, as it is by no means necessary.
>>
>>And again, doesn't it need to be pounded into RDF and OWL somehow?
>
> Thats exactly what the http-range-14 decision is trying to do.
>
> Pat
>
>>
>>>
>>>Pat
>>>
>>>
>>>>
>>>>(But even as I try to wrap this up and hit the send button, I see
>>>>problems with this. For example, the fly (object) buzzing around in
>>>>front of the frog reflects light that physical changes the frogs vision
>>>>transducers in a distinct, fly-like way. When the frog processes this as
>>>>a fly, that is, when the frog's brain puts it in the 'dinner' category,
>>>>it appears very much like it is the very essence of the fly, the fly's
>>>>fly-ness that does so. Any frog that arbitrarily put it in the 'mate'
>>>>category, for example, would lead a very short life.)
>>>>
>>>>John Black
>>>>www.kashori.com
>>>
>>>
>>>--
>>>---------------------------------------------------------------------
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>>>phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
>
>
> --
> ---------------------------------------------------------------------
> IHMC (850)434 8903 or (650)494 3973 home
> 40 South Alcaniz St. (850)202 4416 office
> Pensacola (850)202 4440 fax
> FL 32502 (850)291 0667 cell
> phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
> (06)
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