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Re: [ontolog-forum] Globally unique definitions (was tasteful tags)

To: Pat Hayes <phayes@xxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Fri, 09 Mar 2007 20:36:52 -0500
Message-id: <45F20BB4.8030203@xxxxxxxxxxx>
Pat,    (01)

The global postal address (name, street, city, country)
was adequate as a globally unique id for data transmission
(snail mail) for centuries.  And we've had globally unique
ids for computer-like usage since the 1930s (Social Security
Numbers on punched-card machines).  They also supported data
storage and transmission (by putting cards on a truck and
shipping them to globally unique addresses).    (02)

These techniques may sound primitive by today's standards,
but there is nothing in principle that is different about
URLs except speed and convenience.  On a related note, see
the proposed standard for TCP/IP links via carrier pigeon:    (03)

    http://www.ietf.org/rfc/rfc1149.txt    (04)

That may be jocular, but it could work.    (05)

JFS>> With the advent of computer systems, programming tools
 >> forced those "footnotes" to be made explicit, and they
 >> have done so remarkably well since the 1950s.    (06)

PH> I guess I don't follow what you mean here.    (07)

The globally unique ids such as addresses and SSN's were
put on the computer.  By piling up enough of them, you
could get a unique key for anything in the world you wanted
to designate.  That technique has been used in database
systems for over 40 years.    (08)

Admittedly, the methods were not uniform across all
implementations, they've been working for years.    (09)

PH> There were no global references before the Web.    (010)

No.  See above.    (011)

PH> Well, you can do things like this with redirects and so on.
 > People often don't bother in simple cases, but there is a
 > lot of PHP out there. For example, my URI    (012)

But that involves building an ad hoc redirecting kludge on top
of a global system instead of building an ad hoc global kludge
on top of a local system.    (013)

JFS> I still remember the early days of PCs, in which names
 > of files and disk drives were hard coded in the programs
 > and people complained about those hard coded connections.
 > They pleaded for greater flexibility by parameterizing
 > the connections.  But now the SemWeb has returned to the
 > good (?) or bad (?) old days with hard coded connections.    (014)

PH> Not at all. In fact nothing could be further from the truth,
 > cf http://www.w3.org/Provider/Style/URI    (015)

That reference just recommends some naming guidelines.  What I
was talking about is a context-dependent reference system, which
could be dynamically linked into various contexts.  That is the
typical programming-library notion that programmers have been
using since the early '60s.    (016)

For example, there are two fundamentally different ways of
linking a term, say "vehicle", into an environment:    (017)

  1. Globally unique: a fixed definition that is independent
     of any other definition for "vehicle" in any environment.    (018)

  2. Context dependent: the term "vehicle" is linked to whatever
     definition for "vehicle" is used in the current environment.    (019)

Method #1 is the default for the WWW, and method #2 must be
supported by some ad hoc kludge.  Method #2 is the default for
programming libraries, and method #1 is supported by a variety
of different methods (including the option of using a URI).    (020)

And I'd also like to mention a third approach:    (021)

  3. Unique, but mobile:  a globally unique id, which allows
     agents to move around the WWW while retaining their own
     identity, independent of the computer (or device or cell
     phone) on which it happens to be located -- and without
     any assistance (or even recognition) from the sender or
     the domain name servers of the Internet.    (022)

Method #3 can be simulated by implementing a virtual network
on top of the Internet, and I'm sure that such things will
proliferate over time.    (023)

All of these are important naming schemes, and they should all
be supported by some systematic scheme instead of being built
by an ad hoc kludge (such as a special-purpose PHP program).    (024)

John    (025)

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