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- From: David Brownell <firstname.lastname@example.org>
- To: Paul Prescod <email@example.com>
- Date: Mon, 21 Jun 1999 13:44:57 -0700
Paul Prescod wrote:
> David Megginson wrote:
> > But you cannot always take two references and determine if they do
> > *not* refer to the same object -- that depends on the design.
> "Do these refer to the same object?" => Yes/No/Maybe
> I'm not familiar with a system like that. Can you give an example?
Telephone system. Two phone numbers. Do they refer to the
same person? Hmm, depends on time of day, who happens to pick
up the line, forwarding, and all sorts of exogenous factors.
> Obviously boolean logic is MUCH easier to work with than tri-nary logic.
> Is there a good reason to allow a system fully connected to the Internet
> with access to the URL to return "not proven?"
Yes. I'll commend you to some archives at the OMG for this topic;
I recall something like a four year ongoing discussion about the
notion of identity, which concluded that there are enough different
notions that picking one to use everywhere was wholly impractical.
The class of distinction that always made the most sense to me was
a distinction between extrinsic and intrinsic notions of identity.
Extrinsic notions come from identifiers placed on objects. Intrinsic
ones come from 'within' and are intangible, like souls. Confusion
always arises when people treat extrinsic identities like intrinsic
ones. If you copy something, you have two things which may even
think that their extrinsic identies (identifiers) are the same; but
intrinsically, they are different.
(So if folk on this list are confused by the notion of "identity",
it's understandable and you're in fine company. It's not at all a
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