W3C home > Mailing lists > Public > semantic-web@w3.org > June 2007

Re: What if an URI also is a URL

From: Danny Ayers <danny.ayers@gmail.com>
Date: Wed, 13 Jun 2007 17:51:15 +0200
Message-ID: <1f2ed5cd0706130851v588614dak7d48fce99ccfb462@mail.gmail.com>
To: "Tim Berners-Lee" <timbl@w3.org>
Cc: "Pat Hayes" <phayes@ihmc.us>, "M.David Peterson" <m.david@xmlhacker.com>, r.j.koppes <rikkert@rikkertkoppes.com>, "Yuzhong Qu" <yzqu@seu.edu.cn>, "Sandro Hawke" <sandro@w3.org>, semantic-web@w3.org, swick@w3.org, "John Black" <JohnBlack@kashori.com>
give me a week dan, sorry
i missed  the original question

but i'm pretty sure we know the answer

a week at  most, definitve reply, ok dear?

On 13/06/07, Tim Berners-Lee <timbl@w3.org> wrote:
>
>
> On 2007-06 -11, at 17:09, Pat Hayes wrote:
>
> > Tim, as this discussion gets to the heart of what Ive been trying
> > to argue for several years, please take the comments below as
> > intended in a spirit of analysis rather than just pins and angels.
>
> Ok.  [takes a deep breath].  I'll go down this path with you.
>
> >
> >> On 2007-06 -11, at 13:53, John Black wrote:
> >>
> >>>
> >>> Tim Berners-Lee wrote
> >>>>
> >>>>
> >>>> On 2007-06 -09, at 21:22, M. David Peterson wrote:
> >>>>
> >>>>> On Sat, 09 Jun 2007 07:13:52 -0600, Tim Berners-Lee <timbl@w3.org>
> >>>>> wrote:
> >>>>>
> >>>>>> No. It cannot identify both a document and a person.
> >>>>>
> >>>>> Tim: Will all due respect... WTF?
> >>>>
> >>>>
> >>>> I am using the 'identify' in the strict sense of 'denote'.
> >>>> The semantic web is like a logic language in which URIs are
> >>>> symbols.
> >>>
> >>> Do you believe that by claiming to use the strict, logical sense
> >>> of the word 'denote' you thereby cause or require such
> >>> denotations to be absolute and unambiguous? Where do think
> >>> denotations (or identifications) come from?
> >>
> >> The architecture is that each URI is owned.
> >
> > OK
> >
> >>  With HTTP URIs, this happens through the domain name system and
> >> often  delegation within a domain. Unlike a word, a URI has an
> >> owner.  The owner attempts to make enough information available
> >> that the URI can be used by others without ambiguity in practical
> >> situation.
> >
> > Well now, several points. First, do owners in fact do this? I havnt
> > seen a great deal of such information-providing going on, myself.
> > But OK, fair enough: perhaps you mean, they SHOULD make such
> > information available. But second, more seriously, HOW would they
> > do this? Take your example:
> >
> >> For example, W3C owns http://www.w3.org/People/Berners-Lee/card#i
> >> and has delegated to me the right to say what that URI stands for.
> >
> > OK. So, what DOES that URI stand for? How will you tell someone
> > what the referent is that you intend it to denote, so that they
> > know what to use it for? Now of course, you and I being smart human
> > native English speakers who are reasonably tech-savvy can look at
> > this and figure out that it is probably meant to refer to you. But
> > really, that does depend on us being this smart and savvy.
>
> Well,  I put it in the Tabulator and I get out (among other stuff):
>
>   Tim Berners-Lee
>         Assistant               Amy van der Hiel
>         HomePage                http://www.w3.org/People/Berners-Lee/
>         Work
>                 Address
>                         City            Cambridge
>                         Country         USA
>                         PostalCode              02139
>                         Street          32 Vassar Street
>                         Street2         MIT CSAIL Room 32-G524
>                 Phone           tel:+1-617-253-5702
>                 Latitude                42.361860
>                 Longitude               -71.091840
>         Organization            expandfetchWorld Wide Web Consortium
>
> which to many people gives a fairly lear indication of what is
> identified.  And in fact for non-english speakers, there are words to
> the effect that "Sir Tim Berners-Lee is geboren in Londen in 1955.
> Hij wordt gezien als de bedenker en grondlegger van het World Wide
> Web (WWW), dat was geïnspireerd door HyperCard. Hij werkte hierin
> samen met de Belg Robert Cailliau. Als directeur van het World Wide
> Web Consortium houdt hij toezicht op de ontwikkeling van webtalen en -
> protocollen als HTML, XML, CSS en HTTP. Berners-Lee schreef ook de
> eerste webbrowser, net als het web World Wide Web genaamd, en de
> eerste webserver." and
> Sir Timothy "Tim" John Berners-Lee, KBE (TimBL o TBL). Nacido el 8 de
> junio de 1955 en Londres Inglaterra, se licenció en Física en 1976 en
> el Queen's College de la Universidad de Oxford. Sus padres eran
> matemáticos. Trabajando como investigador en el Laboratorio Europeo
> de Física de Partículas (CERN) de Ginebra, concibió la idea de un
> proyecto de hipertexto global, que años más tarde se convertiría en
> la world wide web.""
>
>
> > It isn't absolutely obvious: and there are many, many web pages out
> > there which I really have no idea what their owners would say they
> > denote.
>
> (Web pages? Web pages are documents.  I wouldn't say they denote
> things.  Symbols, like URIs, denote.
> The URI <http://www.w3.org/People/Berners-Lee/card#i> denotes me, and
> the URI <http://www.w3.org/People/Berners-Lee/card> denotes the web
> page: an RDF one, but a web page.  That web page describes mainly me
> but also to an extent other people and things.)
>
>
>
> >> To use it for something else is an error.
> >
> > But surely if you make this ruling then it is up to you to tell me
> > enough about what it is supposed to be used for, so that I can know
> > when Im making an error. HOW??
>
> Well,  do you want the human way of the machine way?
> - The human way is that you are tempted to use it to represent my car
> but  you see the stuff above, and you realize that for example,
> people would be concerned about the weight property and so on.
> - The machine way could be for example that you operate with an OWL
> system which include the belief that foaf:Person and dot:Car are
> distinct classes, which will flag an error.
>
> >   And what about a URI that I own and wish it to denote, say, the
> > planet Venus, or my pet cat? What do I do, to attach the URI to my
> > intended referent for it?
> >
> >>>
> >>> In my opinion to denote (or to identify) is a verb, something
> >>> that is done by the users of a symbol. After all, symbols (URI)
> >>> are not agents, they don't wake up and choose to denote this or
> >>> that.
> >>
> >> They have wonders which create them for a specific purpose.
> >
> > wonders/owners I presume.
>
> yes
>
> >
> > But the key question to me is, how can they communicate the purpose
> > to the reader? How does one publish an intention? How does one
> > indicate a referent, other than by describing it? How much
> > description is enough?
>
> Experience shows.  This is engineering.
> That question is I suppose one agonized over by working groups all
> the time.
> Fortunately, there are social systems not only for announcing that a
> UTI has been minted and describing what it denotes, but also for
> getting feedback from people who don't understand it, or whose
> machines are not able to process it. This feedback can lead to an
> adjustment of the information out there, publication of tutorials,
> and so on.
>
>
>
> >
> >>> Nor do I think denotation is an attribute or property of a
> >>> symbol, somehow built in or attached when the symbol is first
> >>> conceived. It is more like a dance. I use a symbol to denote
> >>> something expecting you to interpret it to denote the same thing.
> >>> And this coordination, this synchrony of interpretation by both
> >>> sender and receiver, is not always easy. It requires real effort
> >>> to sustain it. The minter of a URI cannot make it happen by
> >>> declaration, nor can a research group or a standards body just
> >>> decree it so.
> >>
> >> In many cases, the URI is defined by connection to already well-
> >> defined sets of things.  In other cases, such as the terms in the
> >> OWL ontology, there was a huge amount of effort and discussion
> >> involved, and the current term is supported by a lot of ongoing
> >> tutorials and so on.  No one said it was easy.  But it is a
> >> different architecture from dance associated with natural language
> >> words.
> >
> > The huge effort was for defining the meanings of the OWL reserved
> > vocabulary, and that is indeed about as defined as a vocabulary can
> > get. But if we just take some OWL ontology and ask how well it
> > constrains the meanings of the new URIs that occur in it, this is
> > *very* much like the word dance that John refers to. In fact in all
> > essentials it seems to me to be pretty much the same game. I
> > publish (say) some stuff which I intend to mean something, you read
> > (hear) it and get some insight into my meaning. You draw some
> > conclusions and if you send (tell) them to me I can check to see if
> > I agree and if not try to send (say) some more to you to make your
> > grasp of my intentions more firm.
>
> Yes, of course the game happens.  But for example when I download my
> OFX bank statements,
> then my computer processes them.  Millions of people do this.  Very
> very few of them worry about who
> did the dance, or do the dance themselves.  Actually, some people
> from banks, Microsoft and Inituit etc did the dance.  This is the
> "total cost of ontologies" argument.
>
>
> >
> > It HAS to be similar, barring machine telepathy. There really isn't
> > anything that either people or machines can do much beyond send
> > symbols to one another: and symbols carry meaning only imperfectly,
> > with inherent ambiguity.
>
> Yes. In theory, there is always a very small possibility that I
> completely misunderstand the way you use a word, say "car", and a
> moderate probability that in some small very rare corner case we
> haven't come across yet, we in pedantic mode would disagree about its
> meaning.
>
> The extent to which I can behave, and build systems, as though in
> fact the terms had well-defied meanings depends on the amount of
> dancing which has been done.   As the dance is done, the structures
> in my brain and those in yours, while never identical, become very
> similar, specifically in that they develop an very strong association
> between a class of real-world object (car) or concept
> (TransitiveProperty).
> Philosophy studies the dance.  (Philosophy has ion the past been
> distracted by a concern that you can't measure the brain's structure,
> and you can't measure an external TranstiveProperty object.  The fact
> htat philsophers have found this difficult doesn't stop the fact that
> it happens, and now we have fMRI machines we are even relieving some
> of this angst. But I digress)
>
>
> The important thing is that as the dance is done, the probability of
> major disagreement, and the degree of pedantic disagreement,
> decrease very dramatically, to become negligible for engineering
> purposes.
>
>
> >>
> >> It is different by design.  The semantic web is an engineered
> >> system, not an observation of nature.
> >
> > But it is a real system, and so it has to obey laws of nature. And
> > there are laws of meaning as well as of physics.
>
> You bring up physics. Indeed.  As an engineer, I design my coffee mug
> to stay in one place: with no wheels. Does it?   It is a real system,
> and  so it has to obey laws of nature.  Physics tells as that at any
> time, there is a finite possibility that any object might just be
> measured to be in a different place, such as a foot to the right and
> no longer around my coffee.  In fact if I study the construction of a
> coffee mug from particles, all kinds of questions arise, as the first
> few particles are very difficult to manage.  I can't even build a
> tool which will tell me where the stupid electron is, without my
> being completely unaware of its momentum.   Given that I can't
> actually claim to have put an electron and proton together with any
> degree of accuracy, how can I claim to be able to build a mug which
> will stay in one place.  Well, it turns out that as the number of
> particles becomes larger, these effects, while still true, just
> become ignorable for engineering purposes.
>
> The analogy is limited, of course.
>
> >>> The reason this matters is that since it requires this effort to
> >>> create a denotation/identification in the first place, it is far
> >>> more sensible, to me at least, to expect that the final
> >>> disambiguation of a symbol be accomplished in the same way, by
> >>> coordinated effort of the parties using the symbol, not by
> >>> declaration of the W3C specifications that all URIs be absolutely
> >>> unambiguous.
> >>> This seems to me to be, as my grandfather used to say, a vain task.
> >>
> >> Your grandfather would perhaps have suggested that an attempt to
> >> define the meaning of common words, as the Académie Française is
> >> set up to do were a 'vain task'.   Many would agree.  But given
> >> that his water came to him though pipes connected, possibly, by
> >> half-inch British Standard pipe-thread connections, and he rode on
> >> rails set a certain distance apart by some committee, and his TV
> >> came for better or worse in 525 or 625 lines as decided by other
> >> committees, he may have respected that the creation of standards
> >> is a very valuable function, and an essential to progress.
> >>
> >> When people meet to define W3C specifications they are not doing
> >> it out of vanity.   They are performing coordinated effort of the
> >> parties who would like to be able to use the symbol.  They are, in
> >> general, users and representatives of users of the symbol.   They
> >> come together to allow those who follow them to use it. They often
> >> work long hours, receiving inadequate recognition for either
> >> products shipped or papers published, the conventional metrics of
> >> performance, so I would not call it vanity.
> >
> > The point surely is that URIs used to refer (not as in HTTP, but as
> > in OWL) do *not* have a standardized meaning. Standards are
> > certainly a chore to create, but they only go so far. OWL defines
> > the meanings of the OWL namespace, but it does not define the
> > meanings of the FOAF vocabulary, or the URIrefs used in, say,
> > ontologies published by the NIH or by JPL.
>
> Ah, so you accept that the OWL working group has effectively given
> meanings to the the terms in the OWL namespace, but you don't think
> that the FOAF friends gave meaning to the FOAF namespace, or the NCBI
> to its ontologies? How curious.  OWL does indeed only go so far.
> FOAF and OFX and so on  go  bit further, but also  only so far.  They
> all create new terms which, modulo arguments afterward an so on,
> become with time an increasingly stable foundation for communication
> between parties.
>
>
> > The only way those meanings can be specified is by writing
> > ontologies: and finite ontologies do not - cannot possibly - nail
> > down referents *uniquely*. No amount   of authority-delegating or
> > standard-setting is going to change this basic fact.
>
> Fortunately, the trains continue to run, and bank statements continue
> to generate graphs and tax forms, more and more people say they
> foaf:knows each other, despite the fact that none of them or the
> relationships have been defined really completely precisely to the
> complete mutual understanding of all parties.
>
> This seems to me to be a very important bridge between philosophy of
> microscopic linguistic interactions of agents, and the large scale
> world of communities with common terms which are 'good enough for
> government work'.  I suppose I am surprised it isn't in the textbooks.
>
> Tim
>
> > Pat
> >
> >
> >
> > --
> > ---------------------------------------------------------------------
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>
>
>


-- 

http://dannyayers.com
Received on Wednesday, 13 June 2007 15:51:32 UTC

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